Praefectus urbi.

About Praefectus urbi

The praefectus urbanus, also called praefectus urbi or urban prefect in English, was prefect of the city of Rome, and later also of Constantinople. The office originated under the Roman kings, continued during the Republic and Empire, and held high importance in late Antiquity. The office survived the collapse of the Western Roman Empire, and the last urban prefect of Rome, named Iohannes, is attested in 599. In the East, in Constantinople, the office survived until the 13th century.