Soviet Nuclear Bunkers in the Czech Republic

History – In brief

After the end of WWII and the collapse of the Third Reich, the territory now belonging to the Czech Republic fell on the Soviet side of the Iron Curtain. Together with today’s Slovakia, it formed the now disappeared unitary state of Czechoslovakia. Despite laying right on the border with the West – including Bavaria, which was part of West Germany and NATO – communist Czechoslovakia enjoyed a relative autonomy from the USSR, until the announced liberally-oriented reforms of the local communist leader Dubcek in the spring of 1968 triggered a violent reaction by the Soviet leader of the time, Leonid Brezhnev (see here). About 250’000 troops from the Warsaw Pact, including the USSR, landed in the Country. As a result, the Soviets established a more hardcore and USSR-compliant local communist regime, and largely increased their military presence.

Similar to the German Democratic Republic (see here for instance), Hungary (see here) or Poland (see here), since then also in Czechoslovakia the local national Army was flanked by a significant contingent of Soviet troops, who left only after the entire Soviet-fueled communist empire started to crumble, at the beginning of the 1990s.

Consequently, for the last two decades of the Cold War, Czechoslovakia was a highly militarized country similar to other ones in the Warsaw Pact (see here). Its geographical position on the border with the West meant it received supply for a high-technology anti-aircraft barrier (see here). Two major airbases in Czechoslovakia were taken over for use by the Soviets and strongly potentiated (see here).

Soviet Nuclear Depots in Czechoslovakia

Beside conventional forces, also nuclear warheads were part of the arsenal deployed in this Country. Where in the late 1960s Soviet strategic nuclear forces were already mostly based on submarine-launched missiles and ICBMs ground-launched from within the USSR’s borders, tactical forces were forward-deployed to satellite countries, to be readily operative in case of war in Europe. Missile systems like the SCUD, Luna (NATO: Frog) and Tochka (NATO: Scarab) were deployed to the Warsaw Pact, supplying either the local Armies or the Soviet forces on site. Typically armed with conventional warheads, these systems were compatible with nuclear warheads too, making them more versatile, and of great use in case of a war against NATO forces in central and western Europe (see here).

Irrespective of their employment by a local national Army or a Soviet missile force, nuclear warheads were kept separated from the rest of the missile system for security, and invariably under strict and exclusive Soviet control. Bunker sites were purpose built in all components of the Warsaw Pact for storing nuclear warheads – see page 46 of this CIA document, showing with some accuracy the location of the corresponding bases.

Granit– and Basalt-type bunkers were typically prepared on airfields or artillery bases, for short-term storage of soon-to-be-launched nuclear weapons. Instead, top-security Monolith-type bunkers (the triangles on the map in the CIA document) were intended for long-term storage of nuclear ordnance.

Monolith-type bunkers were built by local companies on a standard design in the Soviet military inventory, and were implemented in satellite Countries in the late 1960s. Czechoslovakia received three such sites, which took the names Javor 50, by the town of Bílina, Javor 51, close to Míšov, and Javor 52, close to the town of Bělá pod Bezdězem. All three locations are in the north-western regions of today’s Czech Republic.

The Soviet military started withdrawing the nuclear warheads from satellite Countries in 1989, months before the collapse of the wall in Berlin. As for Czechoslovakia, by 1990 all nuclear forces had been moved back to the USSR. Following the end of the Cold War, Monolith-bunkers – similar to most of the colossal inventory of forward-deployed military installations formerly set up by the Soviet Union – were declared surplus by the Countries where they had been implemented.

These primary relics of the Cold War have known since then different destinies. Some of them have been hastily demolished, and together with their associated fragments of recent history, they have almost completely disappeared into oblivion. Luckily, a few are currently still in private hands, and still in existence (see here and here) – specimens of recent military technology, and a vivid memento from recent history, when the map of Europe looked very different from now. Two can be visited, of which one is Javor 51, in the Czech Republic, the main topic of this post. This has been turned into the ‘Atom Museum’, which has the distinction of being the only Monolith-type site in the world offering visits on a regular schedule (the other open site is Podborsko, in Poland, covered here, which is open by appointment).

Also displayed in the following are some pictures of the now inaccessible site Javor 52 in former Czechoslovakia. Photographs were taken in 2020 (Javor 52) and 2022 (Javor 51).

Sights

Javor 51 – The Atom Museum, Míšov

An exceptionally well preserved and high-profile witness of the Cold War, the nuclear depot Javor 51 is a good example of a Monolith-type installation. These bases were centered around two identical semi-interred bunkers for nuclear warheads.

When starting a visit, you will soon make your way to the unloading platform of bunker Nr.1. The shape of the metal canopy, and the small control booth with glass windows overlooking the platform are pretty unique to this site. The metal wall fencing the unloading area is still in its camo coat outside, and greenish paint inside. Caution writings in Russian are still clearly visible. Concrete slabs clearly bear the date of manufacture – 1968. This site was reportedly activated on the 26th of December, 1968.

Even the lamps look original. Some of the – likely – tons of material left by the Soviets on the premises of this site has been put on display ahead of the massive bunker door.

The opening mechanism of the latter is a nice work of mechanics. Four plugs actually lock or unlock the door. They can be moved by means of a manual crank, or likely in the past via an electric mechanism (some wiring is still visible). The thickness of the doors is really impressive (look for the cap of my wide lens on the ground in a picture below for comparison!).

Each bunker had two ground-level entrances to the opposite ends, each with two blast-proof doors in a sequence. Warheads were transported by truck, unloaded beside the entrance of one of the two bunkers, and carried inside through the two doors, which constituted an air-tight airlock.

Today, you can see the inside main hall of the bunkers from the outside during a visit. This was likely not the case in the days of operation. The opening procedure required a request signal to travel all the way to Moscow, and a trigger signal traveling in the opposite direction. Once past the first (external) door with the warhead trolley, that door was shut, and the procedure was repeated for the second door, giving access to the inside of the bunker.

A security trigger told Moscow when the door was open. It can still be seen hanging from top of the door frame.

Once inside, you find yourself on a suspended concrete platform. The warhead trolley had to be lowered via a crane – still in place – to the bottom of the cellar ahead, i.e. to the underground level. The stairs now greatly facilitating visitor’s motion around the bunker were not in place back then, and descending to the underground level for the technicians was via a hatch in the floor of the suspended platform, and a ladder close to the side wall.

On the platform, an original Soviet-made air conditioning system can be seen – with original labeling – and signs in Russian are on display on the walls.

The platform is also a vantage point to see the extensive array of heat-exchangers put along a sidewall of the central hall – atmosphere control was of primary importance for the relatively delicate nuclear warheads. Each of them traveled and was kept in a pressurized canister. However, also the storage site was under careful atmospheric control.

To the opposite end of the bunker, the inner tight door of the second entrance can be clearly seen, ahead of another suspended platform. The warheads left the bunker for maintenance (they might have left also for use, but this never happened, except possibly on drills) from that entrance, which had a loading platform outside for putting the warheads on trucks (this can be better seen in other Monolith sites, like Urkut in Hungary, or Stolzenhain in Germany).

Down on the lower level, the main bunker hall gives access to one side to four big cellars, where the warheads spent their time in storage, and to the other sides to technical rooms. The pavement in the storage cellars features the original metal strongpoints, used to anchor the trolleys for the warheads to the ground. This was in case of a shockwave investing the site in an attack, to avoid the trolleys moving and crashing against one another. The original hooks with spherical joints to link the trolley to the strongpoints are also on display.

The storage cellars today have been used to display informative panels, with many interesting pictures and schemes. These include some from major sites connected with the history of nuclear weaponry in the Soviet Union (like from the test site of Semipalatinsk) and the US (like the Titan Museum near Tucson, AZ, covered in this post).

A few former technical rooms are used to store much original technical gear. This ranges from spare parts, tools and personal gear like working suits left by the Soviets (most with signs in Russian), to items ‘Made in Czechoslovakia’ or even radiation detectors from Britain and the West, gathered here for display and comparison.

Some of these spare parts are wrapped and sealed in Russian, looking like they were cataloged back in the time of operations.

In the main hall, many rare vintage pictures retrace the presence of Soviet military forces on this site as well as others in Czechoslovakia. Magnified copies of rare pictures portray the trucks, canisters and the very warheads likely involved in transport and storage in Javor 51. Actually, much mystery exists around the deployment of nuclear ordnance by the USSR outside its borders (not only to Czechoslovakia). Historical and technical information today made available, even to a dedicated public, is very limited, making this chapter of Cold War history even more intriguing.

Again in the central hall, cabinets for monitoring the nuclear warheads can be seen hanging from the walls, painted in blue. Each warhead used to be stored in a canister, which was periodically linked to these cabinets to check the inner atmosphere, temperature, etc., in order to monitor the health of its very sensitive content.

A large part of the technical/living rooms has been preserved in its original appearance. You can see parts of an air conditioning system, a big water tank, a toilet, a now empty bedroom for the troops. The bunker was constantly manned inside by typically six people, who operated in shifts. They did not sleep there, nor used the toilet much due to poor drainage. However, these facilities were used in drills, and were intended for the case of real war operations, when the bunker might have been sealed from the outside.

The electric cabinets take a dedicated room, like the huge air filters and pumps (Soviet made), installed to grant survival of the people inside the bunker in case of an attack with nuclear weapons or other special warfare. Clearly, the level of safety in the design of the bunker stemmed from the fact that it was considered by the Soviet as a a strategic target for NATO forces.

The last technical rooms host a big Diesel generator, supplied with air from the outside, and a big fuel tank in an adjoining room. Many labels bear writings in Russian, but the generator appears to be made in Czechoslovakia. The bunker was linked to the usual electric power grid of the region, and the generator was intended for emergency operations, in case the grid was lost or the bunker was isolated.

From the technical area, it was possible to access or exit the bunker, via a human-size airlock. The innermost tight door can be seen painted in yellow, with a locking mechanism resembling that of the major tight doors for the missile warheads. Outside the airlock, climbing three levels of ladders was required to get to the surface. This was the normal access to the bunker for the military technical staff, except when warheads arrived or left the storage (this was made via the major entrances, as explained).

Back outside, the second bunker, Nr.2, can be found at a short distance from the former. Nr.2 is being prepared for an exhibition on technology. At the time of writing, it can be toured except for the technical/living rooms. It is in a very good condition, and allows to get similar details as the previous Nr.1 on the construction of this type of facility – including the heating/air conditioning system.

The blue cabinets for plugging the canister for routine status checking and maintenance can be found also in Nr.2 in good shape.

Clearly visible here are the doors closing the technical areas and the warhead cellars. The latter were monitored for security just like the external airtight doors of the bunker, each with a sensor telling controllers whether the cellar was locked or not.

The airlock is covered in soot, possibly the result of a fire. Ahead of the entrance, the unloading platform is very interesting, having a unique set of light doors which had to be opened to allow trucks to come in. The concrete part of the platform appears slightly off-standard, with a short lateral concrete ramp, giving access to the main platform from one side. Parts of missiles – original – are being gathered in this area for display.

Monolith sites include two bunkers, which are the core of a strongly defended fenced area. In Javor 51, fences except the external one have been removed for the safety of visitors (rusty barbed wire can be very dangerous). These can still be found in other similar installations (see here). Similarly, the troops and technicians working on site lived in purpose-built housing, segregated from local communities. In Javor 51, this housing still exists, but cannot be visited.

Leaving the place, you can visit the nice visitor/gathering center, and even find some interesting souvenirs!

Getting there and visiting

All in all, the Atom Museum prepared at Javor 51 is a top destination for everybody interested in the history of the Cold War, nuclear warfare, Soviet history, military history, etc.

Credit goes to the owner of the place, Dr. Vaclav Vitovec, who is leading this remarkable preservation effort, and is a very knowledgeable and enthusiastic guide to the site for those visiting. Dr. Vitovec is also the owner of the border museum in Rozvadov, covered in this post.

The Javor 51 site is actually fairly well known at least to a dedicated public, having been visited by historians, scientists and notable figures – including Francis Gary Powers, Jr., who is very active in preserving the history of the Cold War.

The commitment of the museum’s managers is witnessed also by the nice website (also in English), where you can sign-up for a visit on pre-arranged days – as of 2022, all Saturdays in the warm season – or contact the staff for setting up a personalized visit. It is nice to see a good involvement by the local population (the great majority of visitors on regular visits are Czech), including many from younger generations. The exhibits tell much on the peaceful use of nuclear energy, and this is a major topic in the guided tour in Czech. Actually, the Czech Republic has a strong nuclear tradition, with many power plants in use, and a commitment for the development of nuclear energy in the future.

The location is around 25 miles southeast of Plzen, or 60 miles southwest of Prague. Easy to reach by car. The exact address is Míšov 51, 33563 Míšov, Czechia. Full info on their website. Visiting on a normal scheduled visit is on a partly-guided basis, meaning that you will get an intro (in Czech) of around 40 minutes, than you will be allowed to access the bunkers and visit on your own, for all the time you like. You might end up spending more than 2 hours checking out the site and everything is in it, if you have a special interest for the topic. Dr. Vitovec is fluent in English, and can provide much information upon request.

Javor 52 – Bělá pod Bezdězem

The Monolith-type site Javor 52 has been willingly demolished, likely by the Government of the Czech Republic, as it was the case for most other similar (or more in general, Soviet-related) sites in Poland and Germany.

However, it was hard to get completely rid of any trace of an installation so bulky and reinforced. Therefore, some remains can still be found and explored.

Some technical buildings still in use close to the bunkers may have been there from the days of operation.

Getting close to the bunker area, traces of the multiple fences originally around the site can be found, either in the trees or in the vicinity of unmaintained roads. Wooden or concrete posts with fragments of barbed wire are clearly visible. Also reinforced concrete shooting points can be spotted in the wild vegetation.

As typical, two bunkers were erected on site, and similarly to Javor 51 (see above), in Javor 52 they are aligned, with the entrances all along the same ideal orientation.

The bunkers in Javor 52 have been interred, so that they are now hardly noticeable from the outside, except to a careful eye. Looking inside the eastern one, it is possible to get a view of the open doors of the main airlock, providing a distant view of the inner main hall.

Descending through the lateral human-sized airlock is not possible except for a short length, from a concrete manhole on top of the bunker.

The western bunker is in a better general condition, and the main hall still retains a pretty unique writing in Russian. The ladder descending from the suspended platform has been substituted with a posthumous, regular ladder. Much metalwork has disappeared though, including the heat exchangers, the crane, and the tight doors.

Between the bunkers, a concrete pool can be found – still watertight! – with a function which is hard to guess. A pool for civil use was installed in Stolzenhain (and reportedly also in Javor 52, but I had not the time to watch out for it), but this was in the low-security of the site, far from the bunkers.

Getting there and moving around

Access to this place is possible without violating any property sign, but is clearly not encouraged. Going unnoticed is made tricky by the presence of a public facility nearby – a shelter for foreigners and some education activity. Parking out of sight is possible along the road 27235, north of the complex and to the west of the road – trailheads and corresponding parking areas can be found there. Check out some satellite map to find a way to the exact location of the bunkers – their respective entrances are approximately here (eastern bunker) and here (western bunker).

I visited the site in 2020, and the entrances appeared very dangerous and easy to seal in a permanent way. I do not have any further update, but would suggest to go prepared to find definitively interred and totally inaccessible bunkers.

Javor 50 – Bílina – Quick note

As of 2020, the site of Javor 50 is in a peculiar state of ‘conservation’. The place is closed to the public, but entering would be basically unimpeded, since the external fence to the former military base is mostly collapsed and interrupted. The Soviet quarters insider still have much to offer – including writing in Russian, a scheme of the base, and much more. Likely, the bunkers are also still in a relatively good shape.

Much surprisingly though, somebody is living there with watchdogs, in miserable conditions, keeping visitors out. It is likely that an official visit may be booked by getting in touch with the municipality, since it appears that the site is not used for anything. However I was not successful in connecting with anybody there, therefore I have no suggestion on this point. The of the main entrance is here.

Hitler’s Mystery Mega-Structures in Central Europe

During the last two years of WWII, the Wehrmacht of Nazi Germany was slowly retreating from the eastern front, pushed back by the mighty blows of the Red Army. The bombing runs carried out by the western Allies from airfields in Britain were systematically hitting most urban centers in mainland Germany and over the territory occupied by the Nazis. It is hard to imagine, but it was in the year 1944, when the destiny of Germany was almost sealed, that industrial production in Hitler’s Third Reich reached an all-time record.

At that time the Germans were desperately short of fuel, raw materials and troops, and their production efforts would not spare them from a complete defeat in 1945. Yet it was in the last stages of the war that some of the most ambitious industrial facilities were designed, built and in some cases made operative before the end of the war.

The driver of the design was in most cases the need to move production lines to secluded and well protected areas, difficult to spot and to destroy through air bombing. As a result, these sites were placed far from urban centers. They were also designed to withstand bombing, by putting them underground, or building them with substantial reinforcement, making large use of one of Nazi Germany’s favorite materials – reinforced concrete.

In this chapter two major sites of this kind are described. One is in southwestern Poland, a region which had been part of the German Empire for long before WWII. The second is in eastern Bayern, today one of Federal Germany’s most prosperous states, close to the border with the Czech Republic. Photographs were taken in late summer 2018.

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Sights

Project ‘Riese’, Poland

Construction around this cluster of underground sites started in late 1943, and reportedly lasted until the closing stages of WWII, just days before the Soviets entered the region. The name ‘Riese’ means ‘giant’ in German, and it is surely well suited for this complex, which while far from finished is really striking in size. It was actually composed of at least six major construction sites, which in the intention of their designers should have been developed deeper in the mountains, until a link could be established between them forming a formidable network of tunnels and large halls.

Besides the size and historical meaning of these sites, what makes project ‘Riese’ so fascinating is also the actual purpose of this incredible complex is far from established. Three major theories exist in this respect. The complex might have been intended to be an underground industrial city, a kind of Noah’s Ark for the ‘superior race’ embodied by the top-ranking military and governmental staff of the Reich, or a gigantic secret laboratory for innovative technologies.

What is sure is that the construction was carried out by forced labor, mainly by prisoners of Gross-Rosen concentration camp, just a few miles north of the complex. For the scope, the Nazis created a number of satellite camps next to the entrance of the  construction sites. Rather incredibly, only very scant traces of the project remain in the written records of key figures of Nazi Germany – Albert Speer’s personal diary notably reports some millions marks allocated for project ‘Riese’, and at some point after the war he cited the item resulting from the completion of the construction works, whatever its purpose, as sized to be capable of hosting some tens of thousands people.

Today, six construction sites have been discovered, of which two – Osowka and Rzeczka, the most conspicuous – have been opened to the public, whereas the other are visitable basically for speleologists only.

Osowka

The first visitable site is in the town of Osowka. This site is composed of two parts, one underground with access from the side of a hill, the other close to the top of the same hill.

The underground part can be visited only with a guide. The plant of the completed construction features two accesses, and you will be driven in using the first and out using the other. Between the entrances, the site is mainly composed of an array of parallel tunnels pointing towards the mountain, connected by long halls.

Close to the entrance you can spot a concrete guardhouse with loopholes for machine guns. Some wooden structures like in a mine have been put in place to give an idea of the appearance of the working technique at the time of construction.

Most tunnels have been dug but not reinforced with concrete walls, whereas others are almost complete, showing a peculiar two-level design. The lower level features a smaller section, and the top one a taller, round shaped section.

A feature of the ‘Riese’ complex is a special technique for building the inner concrete coat of the rocky tunnels, producing the distinctive ‘church-ceiling-like’ appearance of some of the halls, with a round shape and frames close to one another.

The Osowka site features also a collection of smaller artifacts, collected from the ground and dating from the construction years, i.e. from late WWII.

Life-size silhouettes of some WWII tanks are on display, to show how the size of these items was totally compatible with the size of the tunnels, in support of a potential use of the site for weapon manufacture.

The outside part, which can be accessed freely, is the most mysterious. At the base of the trail leading uphill you can spot a strange concrete platform, with provision for – possibly – interred pipelines.

Close to the top of the hill you can find a huge concrete platform, with an apparently chaotic ensemble of slots, pipes, handles, stairs and pools. This item has been deemed close in shape to the base of a service building for the valves and pipelines of a power-plant. Theories have flourished in support of the use of this item as a prototype control system for a nuclear power-plant.

The nuclear program of the Nazis, which indeed existed and is even documented to some extent, is shrouded in mystery for what concerns the actual findings obtained during the war. These dark spots are also due to the destruction of most of the hardware connected with the program everywhere in Germany, and with the inherent secret nature of the program itself. No evidence exists of the Osowka site in the public papers about the nuclear studies of the Reich, so the true purpose of this object is likely to remain an unsolved riddle.

Close by this platform, you can find an original concrete building, part of the same construction plan. It is pretty long, with large windows, and likely intended for troops or technical staff.

Rzeczka

Compared to Osowka, this site is more centered on the inside part. Again, there are two entrances, close by a creek on the side of a hill, providing access to a network of tunnels. Similar to Osowka, close by the entrance you can find guard-houses in concrete. These were built soon, possibly for keeping a watch on the forced workers.

The construction works in Rzeczka were less advanced than those in Osowka. Yet thanks to the lack of the concrete coat, you can appreciate the size of the tunnels, some of which are really tall.

There are small collections of artifacts found in the tunnels, and an original concrete room offers a description of all discovered sites of the ‘Riese’ project.

A 1:1 copy of a V-1 German flying bomb has been placed in one of the tunnels, to show the compatibility of the size of this weapon with the tunnel. Such weapons were reportedly assembled in underground facilities elsewhere in Germany.

Visiting is again possible only with a guide. Some multi-media experiences with sounds, lights and voices are included in the tour, but these are not so impressive for those who don’t understand Polish.

On the outside, you can spot some relics from construction years, including trolleys, and concrete slabs watermarked with symbols of the local construction companies tasked with the practical realization of the site. There is also a copy of a V-2 rocket, operative in the last months of WWII but little effective in changing the fate of Nazi Germany.

Getting there and moving around

As pointed out, the sites connected with project ‘Riese’ are many, but most of them are not visitable unless to specialists and with the help of a speleologist. On the other hand, the two sites of Osowka and Rzeczka are professionally operated as primary tourist attractions. The distance from these two sites is about 20 minutes by car, so you can surely arrange the tour of both sites on the same day, with much spare time in your daily schedule.

At Osowka you can find a large parking and a fully equipped visitor center, where you can book a guided tour, or join a departing one – the only way to get inside. Please note that the number of people admitted on each tour is relatively small, so I would suggest booking at least one day in advance through their website (partly also in English) to be sure to get a place at the time you like. They offer several different tours. The most complete include a visit to a part of the underground site which can only be accessed by boat. This is given only on some days by reservation, and only for groups. The standard tour of the inside is offered several times a day.

The guided may turn out really boring, cause you are provided an audio-guide in English with explanations lasting a couple of minutes for each of the circa ten stops, in face of the Polish-speaking guide talking about 5 minutes per site. You may try to spend your spare time taking good pictures, but even though groups are relatively small, they tend to obstruct the view inside, leaving poor chances for acceptable shots. Furthermore, lighting is not very good, so a tripod would be recommended, except you don’t have the time and chance for undisturbed long poses. Therefore, if you are interested in top-level pictures, you would better arrange a dedicated tour out of the normal touristic offer. Otherwise, you’d better go prepared to a difficult visit.

The outside part of the site is less frequented and more rewarding. It can be reached in about ten minutes following a pretty steep, unpaved trail in the trees. This part is unfenced and unguarded.

The Rzeczka site has only an inside part, which can be visited only on a guided tour. You can join one of the frequent tours they provide even without reservation. There is a small visitor center and plenty of parking space. Similar to Osowka, the guide will speak in Polish, and you are provided an audio-guide in English. The visit lasts less than in the case of Osowka, and the audio-guide explanations are more proportionate to the speech of the Polish-speaking guide, making for a more enjoyable visit. The multi-media experiences are of little relevance for non Polish-speaking people. Outside you can find also some panels with explanations on the history of the site in both Polish and English. Website with some info in English here.

The tunnels in Rzeczka are poorly lighted too, so photographing will be difficult unless with a tripod, but the conditions are not very favorable for operating with a tripod – many people around and short times between stops along the tour.

‘Weingut I’ Aviation Industry Complex, Germany

The giant complex known as ‘Weingut I’, the original codename attributed by the Nazi staff at the time of its design and construction, is the direct result of a plan to relocate all major industrial production lines of the Reich to protected areas, far from the line of the front and from any major urban center. In this particular case, the new factory was intended to shelter the production line of the new Junkers Jumo 004 jet engines for the ‘Schwalbe’ – also known as Messerschmitt Me-262, this was the first jet fighter in the world to be pushed into service, back in 1944.

The huge factory was designed based on a basic module made of a reinforced concrete arch, some 250 ft open, 100 ft tall and 10 to 15 ft thick. This item was to be built on site and partly buried under ground level. Twelve such modules were needed for the complete hangar, with a total intended length of the factory of around 1.200 ft. Of the planned twelve sections, seven were actually built between mid-1944 and the end of the war.

Despite the intended scope was that of hiding the factory to protect it from aerial reconnaissance, due to the size of the construction works the object was reportedly spotted by US aircraft, but not attacked. Actually, the special construction was tested against explosives by the US Army after the war, resulting in the collapse of all modules except one, which is still standing today besides the pretty sizable relics of the others.

The site is not actively guarded, but it is located in a regional nature preserve, so access is through a nice walk in the trees. Once next to the hangar you can find multiple access points.

Close to the main arch, the only one still standing, it is possible to find an explanatory panel in German only. It commemorates also the forced laborers from the nearby concentration camps, who had to take part substantially in the construction works.