Civitavecchia is a municipality in the metropolitan city of Rome which overlooks the Tyrrhenian Sea. Its port is among the most important in Italy. It was founded by Trajan in 106 AD. approximately with the name of Centumcellae, as a port of southern Etruria. It was an episcopal seat since the 4th century, then fortified by the Byzantines in the 6th century. Destroyed by the Saracens in the 9th century, the population returned a few decades later, renaming it Civitas vetula. Until 1431 it was a castle and fortified port, then, when besieged, it became part of the Papal State.

During the 19th century, French troops landed there to defend the temporal power of the popes. Both religious and civil architecture are very numerous. The archaeological site of the Taurine Baths is very significant, one of the most important Roman thermal complexes in all of southern Etruria, also known as the Baths of Trajan.