The remains of the ancient fortress Serdika are presented in the underpass between the Presidency and the Council of Ministers in Sofia City. The eastern gate of the fortress has been renovated and exposed within the period 1997-1999.
The town of Serdika was founded 2000 years BC by the Thracian tribe Serdi, who settled in the region around the hot mineral springs. In the 1st century AD the town was conquered by the Romans. During the rule of the emperors Mark Aurelius and Commodus around 175, Serdika was protected by a fortified wall with four gates and observation towers, looking at the four geographical directions of the world.