Sofia is Bulgaria's capital and largest city with a population of more than 1.2 million people. Sofia dominates Bulgaria's economic, social and political scenes. In the 7th century BC, the Thracian Serdi tribe settled here. In the 14th century, Sofia was named after the basilica St. Sofia, the oldest East-Orthodox Church in the city, built by Byzantine Emperor Justinian in the period 527 – 565 AD. During five centuries of Ottoman rule the church had been turned into a mosque. Beside the wall of the church is the Tomb of the Unknown Soldier. After a devastating earthquake in the 19th Century, the church was abandoned and only in 1900 was it restored in full. Vitosha Mountain is on the south part of the town.