The curved, colonnaded, neoclassic former County Hall that once housed London's local government administration is now home to a superb three-level aquarium full of sharks and stingrays, along with more than 500 other aquatic species, both common and rare. There are also feeding and hands-on displays, including a tank full of shellfish that you can touch. It's not the biggest aquarium you've ever seen, but the educational exhibits are particularly well arranged, with areas for different oceans, water environments, and climate zones, ranging from a stunning coral reef to a rain forest. Regular feeding times and free talks are offered throughout the day. There are also special "experiences" that include behind-the-scenes tours, snorkeling with sharks, or turtle feeding at an extra charge. Admission is by timed slot, but you can purchase flexible priority-entry tickets that also avoid the long lines.