Zivilschutzbunker Köln-Kalk, Cold War deep bunker in Kalk, Germany

The Zivilschutzbunker Köln-Kalk is a two-level civil defense facility built in 1979 beneath the Kalker Hauptstraße, sharing its structure with the Kalk Post U-Bahn station. Its inner bunker is encased in 1.40-meter-thick concrete, with a 75-meter corridor leading to a first-aid room, an operating-capable sick bay, and 354 four-tier seat-and-berth units. The 4,000-square-meter space was dimensioned for 2,366 people, or 1.7 square meters each.

The shelter was built in 1979 during the Cold War as a civil defense facility against nuclear, biological, and chemical threats. It represents a period when such protective structures were constructed across Western Europe as serious emergency measures.

The bunker's name comes from its Cold War role as a Zivilschutz-Mehrzweckanlage, a civil protection multi-purpose facility. Since 2016 it has been run by volunteers from the Dokumentationsstätte Kalter Krieg, a spin-off of the Cologne Fortress Museum, who open it for visits on the first Sunday of each month. A virtual 3D tour was created because of the long waiting list.

The bunker is open for visits only on the first Sunday of each month, run by volunteers of the Dokumentationsstätte Kalter Krieg association. Because the waiting list is long, a virtual 3D tour is available online. The technical systems have not been maintained since the facility was decommissioned in 2005.

The bunker's emergency plan also covered the tram: in a crisis, trams were to enter the station from both sides and house 432 people, while field beds for 354 more were set up in front of the kiosk and on the platforms one floor below.