Capitol of the Western Roman Empire. Note that I say Western because you might not know it but Rome was divided into 2 Empires for it to be easier to manage. Unlike the Western Empire the East survived through the Dark Ages. The east was the Eastern Empire or sometimes called the Byzantine Empire. It's capitol was Constantinople, modern day Istanbul.
Rome, you'll never find a more wretched hive of scum and villainy(at least in the 8th century).