National Polytechnical Museum
The National Polytechnical Museum () is a science museum located in Sofia, Bulgaria. History. The National Polytechnical Museum was established on 13 May 1957 by a Council of Ministers decree, initially under the Bulgarian Academy of Sciences. It was declared a national museum in 1968. Since 1992, the museum is located in a building formerly used as a museum to Georgi Dimitrov. It has been completely renovated in 2012 at a cost of 640,000 lv (326,000 euro). The National Polytechnical Museum regularly participates in the annual Night of Museums. Collections. The museum has a collection of more than  22,000 items, but only 1,000 of them are permanently displayed. Collections are supplemented by a library with more than 12,000 books and journals, and an archive of about 2,000 documents. Permanent collections are divided in exhibitions of time measurement, transportation, photography and cinema, optics, audio equipment, radio and television, computing equipment, communications equipment and others. Some of the items on display include: Accessibility. The museum is located on ul. Opalchenska 66. It is open from Monday to Saturday from 9 to 17 o'clock. Fees range from 1 to 7 leva; fees for laboratory demonstrations are 10 or 15 leva (for  groups of more than 10 people). Branches. The National Polytechnical Museum has three branches outside Sofia. One of them is the hydroelectric power station in Pancharevo, the first power producing unit in Southeastern Europe. It became operational on 1 November 1900 and powered the tram system of Sofia, street lamps and several industries. The station was declared a site of cultural significance in 1986, shortly after it ceased operations. The two other branches are a textile museum in Sliven, which traces the history of textile crafts, fabrics and techniques in Bulgaria through the centuries, and a Palace of physics in  Kazanlak.