Around 30 AD, Histria became a Roman town. During the Roman period from the 1st to 3rd centuries AD, temples were built for the Roman gods, besides a public bath and houses for the wealthy. Altogether, it was in continuous existence for some 14 centuries, starting with the Greek period up to the Roman-Byzantine period. The Halmyris bay where was the city founded was closed by sand deposits and access to the Black Sea gradually was cut. Trade continued until the 6th century AD. The invasion of the Avars and the Slavs in the 7th century AD almost entirely destroyed the fortress, and the Istrians dispersed; the name and the city disappeared.

(http://en.wikipedia.org/wiki/Histria_%28ancient_city%29)