Flak tower

Flak towers (German: Flaktürme) were eight complexes of large, above-ground, anti-aircraft gun blockhouse towers constructed by Nazi Germany in the cities of Berlin (3), Hamburg (2), and Vienna (3) from 1940 onwards. Other cities that used flak towers included Stuttgart and Frankfurt. Smaller single-purpose flak towers were built at key outlying German strongpoints, such as at Angers, France and Helgoland, Germany.

The towers were used by the Luftwaffe to defend against Allied air raids against these cities during World War II. They also served as air-raid shelters for tens of thousands of local civilians.

After the RAF's raid on Berlin in 1940, Adolf Hitler ordered the construction of three massive flak towers to defend the capital from air attack. Each tower had a radar installation with a radar dish which could be retracted behind a thick concrete and steel dome for protection.

Hitler was interested in the design of the towers, and even made some sketches. They were constructed in six months. The priority of the project was such that the German national rail schedule was altered to facilitate the shipment of concrete, steel and timber to the construction sites.

With concrete walls up to 3.5 m (11 ft) thick, flak towers were considered by their designers to be invulnerable to attack by the standard ordnance carried by RAF and USAAF heavy bombers at the time of their construction.

The towers were able to sustain a rate of fire of 8000 rounds per minute from their multi-level guns (albeit mostly smaller-caliber shells, such as the 20mm 2cm FlaK 30), with a range of up to 14 km (8.7 mi) in a 360-degree field of fire. However, only the 128 mm (5.0 in) guns had effective range to defend against the RAF and USAAF heavy bombers. The three flak towers around the outskirts of Berlin created a triangle of anti-aircraft fire that covered the centre of Berlin.

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