Sofia is the biggest and the most developed city and district in Bulgaria.

Founded seven thousand years ago, Sofia is the second oldest city in Europe. It has been given several names in the course of history and the remnants of the old cities can still be seen today. Serdika was the name of the central dwelling of the ancient Thracian tribe known as Serdi. It bore that name when it became part of the Bulgarian state at the beginning of the ninth century and was soon recognized as one of the most important feudal towns, acquiring the Slavic name Sredets. Near Sofia lies Boyana church, which is one of the most valuable memorials of Bulgarian and European culture. The church boasts frescoes, acclaimed by specialists as “the best examples of eastern mediaeval art during its twelve century history”. The decline of Sofia during the Ottoman Empire was followed by the rejuvenation after the liberation in 1879, when Sofia was chosen as the capital of Bulgaria at the First National Constituent Assembly. The plans of 1881-1882 were followed by a brisk and straight-forward period of construction.

Sofia city district is the only district with one municipality. The municipality includes three towns – Bankya, Novi Iskar and Buhovo, and 34 villages. It is bordered by Pernik and Sofia district. District Sofia city is located in the Sofia plain, 550 m above sea level.