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 railway lines to Sofia, Panagyurishte, Karlovo, Peshtera, Stara Zagora, Dimitrovgrad, and Asenovgrad. There are three railway stations: Plovdiv Central, Trakia, and Filipovo as well as a freight station. Plovdiv has a large public transport system including around 29 main and 10 extra bus lines. However, there are no trams in the city, and the Plovdiv trolleybus system was closed in autumn 2012. Six bridges span the Maritsa river including a railway bridge and a covered bridge. There are important road junctions to the south, southwest, and north. Plovdiv has a well-developed cycling infrastructure which covers almost all districts of the