Situated on just 13 hectares, Frankfurt's typical city zoo shows a variety of very rare and special species, and some unique buildings. Limited space led to specializing in choice collections that are presented by means of sophisticated techniques. At the Exotarium, climatic landscapes and endangered reptiles can be seen. The Grzimek House is famous for its nocturnal displays, and the zoo's multiple-generation propagation of apes is world-renowned. For ape and bird displays, historic innovations were made.