Prince Alexander of Battenberg Square (Bulgarian: площад „Княз Александър Батенберг“), often called simply Battenberg Square (площад „Батенберг“) is the largest square of Sofia, the capital of Bulgaria. It is named after Alexander Joseph of Battenberg, the first prince of modern Bulgaria, and is arguably the most suitable place in Sofia for major open-air concerts such as the concert series "Opera on the Square", manifestations, parades (including the military parade on St George's Day) and other large-scale events. During the Communist rule of Bulgaria, the square had the name 9 September Square, as a coup on 9 September 1944 made the country a Communist state. It was the site of the Georgi Dimitrov Mausoleum from 1949 until 1999. Before 1944, the square was known as Tsar's Square because the former royal palace, now the National Art Gallery, is located there.
