The bunker was erected on a concrete foundation slab 2.4 m thick and measures 66.3 x 48.9 m. The outer walls are 165 cm thick, resulting in an internal area of 2872.8 square metres. Forty columns, each measuring 3 x 2.4 m, which support and stabilise the bunker construction, take up a further 288 square metres, almost a tenth of the available interior. This leaves some 7500 square metres working area spread over the three floors.

Some 35,000 cubic metres of concrete, weighing some 85,000 tonnes, went into the bunker’s construction. Today, the facility has a market value of some 2.5 million euros – and that does not include the rebars and other reinforcements used. The concrete cube was heavily “impregnated” with rebars and its exterior was surrounded by 8 mm thick steel plates. These were intended to neutralise the effects of an electro-magnetic pulse resulting from a nuclear explosion. The individual floors in the bunker are relatively thin at 60 cm. Even the actual “roof” of the bunker is frighteningly thin at only 75 cm thickness. However, there is a second ferro-concrete slab above it, the blast cap. With a thickness of 4 m in places, this represents the real protection for the bunker against conventional weapons. Should the blast cap collapse as a result of a direct hit, it will fall down onto a thick layer of sand in the gap between the blast cap and the bunker roof. To prevent conventional weapons detonating in the immediate vicinity of the bunker, the blast cap extends some 20 m on all sides beyond the actual bunker dimensions.

Sensitive areas within the bunker are suspended from their respective ceilings. When the bunker was designed, it was assumed that a nuclear explosion in the vicinity of the bunker could cause it to shift its position by up to 40 cm. The bunker’s resulting acceleration forces would have been extremely high. For this reason, areas where personnel would have operated and where vital machinery is located have been incorporated into totally enclosed platforms which are suspended on large springs from the ceiling. The platforms and their enclosures can thus swing 40 cm in all directions, thus compensating for any sudden bunker shift. Some of the platforms are more than 500 square metres in area and had to be built around the supporting pillars mentioned above: a minimum clearance of 40 cm was observed here as well.

All aspects of daily life had to be considered and dealt with in order to ensure that those inside the bunker would be able to survive a prolonged period in it without supplies and provisions from outside. In addition, state-of-the-art communications facilities were installed. A deep well in the bunker, together with a waterworks, would have met water requirements. Several large tanks in the waterworks complex had a total storage capacity of some 350,000 litres of water, with the bulk of it being required for cooling purposes.

Air is supplied via an intake opening which is protected by an extremely thick concrete cover. In the same way, the air is exhausted via a further protected opening. Once inside the bunker, the air passed along various ducts: air for the diesels was provided without any major filtering. Following a nuclear strike, the air for the emergency standby set would only have been cooled. To this end, the air was passed through a large set of pipes cast in concrete (mass cooler). As a result, the machine room would have become contaminated. What would not have troubled the diesel generators, would have been unthinkable, however, for the working areas.

The breathing air for the normal working areas was therefore subject to extensive filtering and only then fed into the bunker where it was constantly tested. Directly after a nuclear strike, the bunker would have been sealed shut for 36 hours as the hot air outside could not have been sufficiently cooled and it would have, therefore, burnt out the filters. The whole of the bunker was operated at an overpressure so that any air escaping via possible leakage holes or cracks would prevent the ingress of chemical or biological agents or radioactive dust.

These and many other technical operations and sequences were monitored and controlled in the “heart” of the bunker, the “dispatcher’s” room. Around it is the bunker’s electrical plant to be found as a constant source of electricity was essential for a command centre such as 5001: under no circumstances could a power failure be tolerated. For this reason, there was not only the normal grid supply and the emergency power supply based on the diesel generators, but also an uninterrupted power supply (UPS) source via batteries. Since the bunker operated on 220 V AC, a DC generator ran constantly, driving an AC motor running at no-load. Should the grid supply fail, this combination would have converted the DC battery supply to AC to provide the necessary power requirements while the standby generators came on power and were synchronised, an operation taking less than four minutes. The batteries would then be at the end of their capacity and power would have been switched to the generators.

The 5001 bunker is really like a mini-town which could function independently for some 14 days. In addition to the water, air and electrical supplies, there were also air-conditioning systems, washing and toilet facilities, a medical centre with an emergency operations room, a decontamination area and a large kitchen available. Up to 400 personnel could have survived for two weeks. However, what would have faced them outside? A devastated, empty world. Fortunately, things turned out differently.

The cold war is a thing of the past so, instead of entering the bunker in a state of fear, we can take a look at one of today’s most impressive bunkers – the Honecker bunker.