Veii was the first Etruscan town to fall into the hands of the Romans in 396 BC, followed by Roselle, Tarquinia and Vulci in 280 BC. The Etruscan kingdom in Maremma disappeared in a few decades and the whole region passed under the control of Rome. It is certainly true that the Romans destroyed many Etruscan settlements; however, they also founded many important towns, including Cosa, on the promontory of Ansedonia (273 BC), and modernized the port and road networks realizing the Aurelia, Aemilia Scauri and Clodia roads. The last road connected Saturnia to Rome.

The Romans also founded many thermal sites, whose names testify to their Latin origins, as is the case of Saturnia. In Roman times the thermal baths were places open to even to worse-off people where men and women dedicated to the well-being of body and mind and could socialize. If you are having your holidays in Maremma , just a plan a visit to the ruins of the many Roman thermal baths, such as the baths of Betitio Perpetuo Arzygio in Roselle.

In Roman times, and especially from the 1st century BC, developed the system of latifundia, based on pieces of property covering very large land areas. Intensive agriculture for the production of cereals replaced the subsistence form of farming practiced in small estates.

With the development of the new system, people abandoned the countryside and moved to towns. With nobody taking care of the channels, hydrogeological instability affected Maremma coastal plains for many centuries.

Due to the competition of the most peripheral provinces of the empire, the system based on the latifundium experienced a crisis in the 2nd century, which lead to a progressive and inexorable economic decline.