The Berlin Zoological Garden is the oldest surviving and best-known zoo in Germany. Opened in 1844, it covers 35 hectares and is located in Berlin's Tiergarten. With about 1,380 different species and over 20,200 animals, the zoo presents one of the most comprehensive collections of species in the world. The zoo and its aquarium had more than 3.5 million visitors in 2017. It is the most-visited zoo in Europe and one of the most popular worldwide.