Very interesting to me . No doubt they are technically ugly to most and much study done as to how to remove them . To me they are the donjons and keeps of their time. I well remember reading the " A Distant Mirror"" by Barbara Tuchman. Medieval donjons are uncannily similar to flak towers. I find a odd power and indeed meanacing odd beauty in these towers. The British architects Alison and Peter Smithson toured the Atlantic Wall just after the war and created the term "Brutalism" to describe a rash of new buildings that were inspired by these buildings of war. If you thought architecture was a civil art, think again. Crazy people everywhere. I would not be inspired to emulate them in modern design but I do find them impeling to view and study. I believe there or 6 or 7 in Vienna orf varying types. http://www.msn.com/en-us/travel/tripideas/forget-grand-architecture-%E2%80%93-vienna-embraces-its-ugly-side/ar-BBj3zNw
There's 6 of them (3 "pairs" of 2). I've seen them all at one point or another: Augarten Park: You're free to walk around both. The gunnery tower is heavily damaged as a result of an explosion in 1946, and some of the upper platforms were removed in 2007 due to safety concerns. I was there when they were doing this. The fire control tower is completely intact. Arenberg Park: Both the gunnery and fire control towers are completely intact and you are free to walk around them. Stiftskaserne: The fire control tower has been turned into an aquarium (I've never been inside) and the gunnery tower is on an Austrian military base and is apparently used for storage. The Augarten and Stiftskaserne Flak Towers are the so-called "3rd generation" models. The Arenberg pair are second generation models. 2nd Generation (Arenberg): 3rd Generation (Augarten):