Silistra

Silistra is a port city of northeastern Bulgaria, lying on the southern side of the lower Danube at the country's border with Romania. Silistra is the administrative centre of Silistra Province and one of the important cities of the historical region of Southern Dobruja.
Founded as a Roman fortress named Durostorum (or Dorostorum) in AD 29, the settlement became an important military centre of Moesia and grew into a city at the time of Marcus Aurelius. In 388, Durostorum became the seat of a Christian bishopric and a centre of Christianity in the region, and Roman general Flavius Aëtius was born in the town in 396. After the Roman Empire was split, the town (known as Δουρόστολον, Durostolon in Byzantine Greek) became part of the Byzantine Empire.
http://en.wikipedia.org/wiki/Silistra