Prince Alexander I Square (Bulgarian: площад „Княз Александър I“, Ploshtad "Knyaz Aleksandar I"), 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 (Alexander I of Bulgaria), 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", demonstrations, parades (including the military parade on St George's Day) and other large-scale events.