Haus des Meeres, Flakturm Esterhazypark

A marvelous zoo, with a rain forest glasshouse, tiny apes, aquariums with sharks, and terrariums with reptiles and venomous snakes. It is in one of the surviving air raid shelters from WWII, a so-called ''Flakturm''. The building formerly housed some of the first radar equipment, and is designed to withstand a direct bomb hit, an earthquake, and wind speeds up to an overpressure of ten bar. Now there is also a platform on top affording nice views over the roofs of Vienna.