Copenhagen Zoo is one of the largest zoological gardens in Europe. It was founded in 1859 by ornithologist N. Kjærbølling, and was then a part of Frederiksberg Have. The landmark of the zoo is a tall watch tower (43.5 metres) and currently the garden where the Children's Zoo is located, is inhabited with animals like goats, cows and rabbits. Copenhagen Zoo contains over 2,500 animal and bird species from all over the world. In recent years great work has been carried out in order to create more space to create believable natural surroundings for the animals. In 1998, Christian Cold designed the new entrance, which is a piece of interesting modern architecture. Another highlight at the Zoo is the Tropical House consisting of rare birds and butterflies in their natural surroundings. Check out the boa constrictor and the poisonous spiders as well.