Apart from the fun of seeing elephants, hippos, penguins and more, Antwerp's zoo draws crowds because of its history. One of the world's oldest zoos, the site is classified as a historical monument but combines traditional architecture with up-to-date animal habitats. Even if you're not going to go in, it's worth taking a look at the magnificent entrance gate. If you do, be sure not to miss the "Egyptian Temple," built in 1856, and the faux-Oriental okapi building. More modern structures include Hippotopia, built in 2003.