The National Archaeological Museum (Bulgarian: Национален археологически музей, Natsionalen arheologicheski muzey) is an archaeological museum in the centre of Sofia, the capital of Bulgaria. It occupies the building of the largest and oldest former Ottoman mosque in the city, originally known as Koca Mahmut Paşa Camii. The construction started in 1451 under grand vizier Veli Mahmud Pasha but due to his death in 1474 the mosque has been completed in 1494. The museum was established as a separate entity in 1893 as the National Museum directed by Czech Václav Dobruský with its headquarters in the former mosque that previously housed the National Library between 1880 and 1893.
Source: Wikipedia