For animal lovers, a visit to the zoo is a double bonus: a chance to see your favourite critters up close in a near-natural environment, and to support the conservation and research activities funded by your entrance money. And there are plenty of dedicated, beautiful zoos out there for you to discover. Spot rare Amur leopards at Philadelphia Zoo, the oldest in the US, or watch orangutans at play from a boardwalk at Singapore Zoo. Hippos and penguins frolic underwater at the gigantic Berlin Zoo, while crocodiles lurk menacingly beneath the surface at Australia Zoo, founded by the legendary conservationist Steve Irwin. And at Chester Zoo in northern England you can even bring your childhood dreams to life by experiencing what it's like to be a zookeeper for a day!