The Ancient Thracian and Roman city of Serdica is the precursor of the contemporary Bulgarian capital Sofia. The oldest traces of civilized life in Sofia are from a Neolithic settlement dated back to 5000 BC located in today’s Slatina Quarter. There are also traces of life from the Charcolithic (also known as Aeneolithic or Copper Age) and the Bronze Age. After the Bronze Age the Sofia Valley was inhabited by the Ancient Thracian tribe serdi (some believe them to have been a Celtic tribe) which gave the name to the Ancient Thracian settlement called Serdica or Sardica.
The city of Serdica was conquered briefly in the 4th century BC by Philip II of Macedon and his son Alexander the Great. Around 29 BC, Sofia was conquered by the Romans and renamed Ulpia Serdica. It became a municipium, the center of an administrative region, during the reign of Emperor Trajan (r. 98-117), and saw extensive development with many new buildings. It is known to have been the favorite place of Roman Emperor Constantine I the Great who used to say, “Serdica is my Rome”.
In 343 AD, the Council of Serdica was held in the city, in the 4th century church that preceded the current 6th century St. Sofia Basilica. In 447 AD, the city was destroyed by the Huns. During the reign of Byzantine Emperor Justinian I (r. 527-565 AD), a new fortress wall was built whose remains have been excavated and can be seen today. This is when it was renamed Triaditsa. It became part of the First Bulgarian Empire (632/680 – 1018 AD) in 809 AD when it was conquered by Bulgaria’s Khan Krum, and was known by its Slavic-Bulgarian name Sredets until the 14th century when it took the name of the St. Sofia Basilica.