Haus des Meeres – Aqua Terra Zoo

One of Vienna's most unique attractions is housed in a massive former WWII flak tower. This 11-story complex is home to over 10,000 animals: on the tropical rainforest level, you can encounter monkeys and birds, while in the giant aquariums, sharks and sea turtles swim right before your eyes. For the daring, the terrariums showcase a world of snakes, crocodiles, and spiders. The rooftop terrace and café on the top floor offer arguably the best 360-degree panoramic view over the city of Vienna.