Great images! There were only three Flakturme built in Berlin, Flakturm I at Zoologischer Garten, Flakturm II at Friedrichshain and Flakturm III at Humboldthain. Based on the disposition of buildings in the background of the lowest image, this is Flakturm III, which was located to the north of the city centre. The orientation of the Rotes Rathaus, the tower at centre above the 'O' in th word Original with the Berlinerdom behind the steeple above the I in Original places the tower as Nr III. The caption is not accurate, however. The Berlin Flakturme were not armed with 8.8 cm guns, but, as quoted from a translated letter to Reichsmarshal Goring from Hauptmann von Below dated September 9 1940 "on each tower there are to be four twin 10.5 cm naval guns, several 3.7 cm and 2 cm guns." The 10.5 cm guns were later changed to 12.8 cm guns.
