A volunteer association runs tours through the warren of bunkers, air-raid shelters and tunnels under Gesundbrunnen station — one of the most compelling ways to understand twentieth-century Berlin. The standard tour winds through a preserved wartime civilian shelter, complete with luminescent paint, original signage and equipment, and explains how the city's underground was used through the war and the Cold War.
Other tours cover the bunkers of the Cold War, the tunnels dug under the Wall by escapees, and the "ghost stations" where Western trains rolled through sealed Eastern platforms. Tours run in several languages but book out fast; reserve ahead, and bring warm clothes — it is cold below ground year-round.