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 the Slavic name began to appear as "Papaldiv/n Plo(v)div, Pladiv, Pladin, Plapdiv, Plovdin", which evolved from a Thracian variant "Pulpudeva". As a result, the name has lost any meaning. In British English the Bulgarian variant "Plòvdiv" has become prevalent after World War I. The Crusaders mentioned the city as "Prineople", "Sinople" and "Phinepople". The Ottomans called the city "Filibe", a corruption of "Philip", in a document from 1448. Plovdiv is located on the banks of the Maritsa river, southeast of the Bulgarian capital Sofia. The city is in the southern part of the "Plain of Plovdiv", an alluvial plain that