One of three anti-aircraft towers built to defend Berlin from the air, and the only one left partly standing. French engineers tried to destroy it in 1948 with 41 tonnes of dynamite over three attempts — and then deliberately spared what was left, not out of restraint, but because the wrecked section sat beside a railway line under Soviet control at the start of the Berlin Blockade.
At a glance
The Humboldthain flak tower is one of a pair — a combat tower (Gefechtsturm) and a smaller command tower (Leitturm) — built in Berlin’s Gesundbrunnen district as part of a citywide system of three such pairs, ordered directly by Hitler after the first RAF raids on the capital. Built in just six months by a workforce of up to 3,200, the combat tower carried four twin 128mm anti-aircraft guns and could shelter roughly 15,000 civilians; the command tower held another 7,500.
Postwar demolition levelled the command tower and part of the combat tower, but stopped short of finishing the job. What survived is now buried inside an artificial hill in the Volkspark Humboldthain, its exposed south wall open to guided tours since 2004.
Key facts
- Built: October 1941 to April 1942, in around six months, by up to 3,200 workers including foreign labourers, conscripts and prisoners of war working around the clock.
- Dimensions: combat tower roughly 70 by 70 metres and 42 metres tall, walls up to 2.5 metres thick, roof and floor slabs nearly 4 metres; command tower roughly 23 by 50 metres.
- Armament: four twin 128mm heavy anti-aircraft guns on the combat tower’s roof, plus lighter flak against low-flying aircraft.
- Shelter capacity: sources give slightly different figures, but the combat tower is generally put at around 15,000–16,000 civilians and the command tower at a further 7,500.
- Postwar demolition, 1947–48: French occupation forces (Humboldthain lay in the French sector) detonated 41 tonnes of dynamite across three attempts; the first, on 28 February 1948, failed outright. Only the third, on 13 March 1948 with 25 tonnes, brought down the tower’s southern half.
- The northern half was deliberately spared: a railway line immediately north of the tower was under Soviet control, and French engineers judged the risk of damaging it — in the tense months of the Berlin Blockade — too high to continue.
- Today: three of the surviving structure’s seven floors are open on seasonal guided tours (April–October) run by Berliner Unterwelten e.V.; the exterior wall is used as a climbing wall by the German Alpine Club, and the site hosts a protected bat hibernation roost, which limits winter access.
- Coordinates: 52.5473° N, 13.3847° E.
How it was built
Humboldthain was one of three matched pairs of flak towers Hitler ordered built across Berlin after the first British air raids in 1940, alongside towers at the Zoo and at Friedrichshain. Up to 3,200 workers, including foreign labourers, conscripts and prisoners of war, built the combat tower and its smaller command tower in around six months of continuous work — a pace that left the finished structure with walls and roof slabs thick enough to withstand direct hits from contemporary bombs, sheltering tens of thousands of civilians beneath its gun platforms.
Who tells it, and where the accounts diverge
The standard telling of Humboldthain’s postwar history is that the Allies tried and failed to demolish it — a story that implies the tower simply proved too strong. The documented sequence says something more specific: French engineers succeeded in bringing down the southern half of the combat tower on their third attempt, using 25 tonnes of dynamite, and then stopped. What remained standing did so because a Soviet-controlled railway line ran immediately alongside it, and in 1948 — the year of the Berlin Blockade — damaging that line was a political risk the French occupation authorities were not willing to take. The tower survives less as a monument to Nazi engineering than as a structure the emerging Cold War made too dangerous to finish erasing.
What you see today
- The exposed south wall and three surviving floors of the combat tower, accessible on guided tours.
- The artificial hill of the Volkspark Humboldthain, built up from wartime rubble over the buried remainder of the structure.
- A climbing wall on the tower’s exterior, run by the German Alpine Club.
Getting there
The Volkspark Humboldthain is in Berlin’s Gesundbrunnen district, a short walk from Gesundbrunnen station; guided tours of the tower’s interior run seasonally, April to October, booked through Berliner Unterwelten e.V.
Sources
- Berliner Unterwelten e.V. (berliner-unterwelten.de) — construction, dimensions, armament, shelter capacity, guided-tour access.
- Subterranea Britannica (subbrit.org.uk) — cross-check on dimensions and postwar chronology.
- English Wikipedia, Volkspark Humboldthain — workforce figures, postwar demolition and park landscaping.
- The Berliner, on the 1947–48 French demolition attempts and the railway line that stopped them.
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