There is a tv program on either the History Channel or the Military Channel in the Battlefield series. They are rerun fairly often. Each program is 2 hours. The one on Battlefield Berlin spends some time on the 3 mutually supporting flak towers in Berlin. It is hard to believe they could build something that could withstand the heaviest Russian artillery. Of course, if the Russian guns could see the tower (but because of trajectory not hit the 88s on the roof) then the 88s could see the Russian guns. The towers were sited to have excellent unobstructed fields of view over long distances. I believe the Germans even knocked down buildings to achieve this. There was no sneaking up on the towers.
A tower would be a great piece - even just one wall and part of the roof. But even a 4 storey + roof version would be over 2 ft. high. And the cost with a few 88 guns, 20 mm antiaircrat guns and some soldiers would be huge. That is the type of shock and awe piece Figarti might do, but I really cannot see anyone else doing.
Terry