Plovdiv 40,000 objects. The Museum of Natural Science was inaugurated in 1955 in the old edifice of the Plovdiv Municipality built in 1880. It is among the most important museums in the country with rich collections in its Paleontology, Mineralogy, and Botanic sections. There are several rooms for wildlife and it contains Bulgaria's largest freshwater aquarium with 40 fish species. It has a collection of minerals from the Rhodope mountains. The Museum of Aviation was established on 21 September 1991 on the territory of the Krumovo airbase to the southeast of the city. The museum possesses 59 aircraft and indoor and
Plovdiv Arts; and others. The 2009 International Olympiad in Informatics (IOI) was held at the University of Plovdiv "Paisiy Hilendarski", between 8 and 15 August 2009. The 2009 IOI Honorary Patron was Bulgarian President Georgi Parvanov. Between 1875 and 1906, the Zariphios School was one of the local Greek educational institutions that provided elementary and secondary education. Plovdiv Sports Complex consists of Plovdiv Stadium with several additional football fields, tennis courts, swimming pools, a rowing base with a 2 km-long channel, restaurants, and cafés in a spacious park in the western part of the city just south of the Maritsa river.