The ancient city of Roselle stood on an elliptical hill comprising two reliefs separated by a median valley, the heart of the political and religious life of the community in all eras. Although there are traces of frequentation during Prehistory and Protohistory, Roselle was urbanized by the Etruscans in the 7th century BC. The choice of this area for an organized settlement was not accidental. In fact, the elevated position allowed the natural defense of the place and the control of the current plain of Grosseto, formerly occupied by Lake Prile, a large lagoon communicating with the sea. The Etruscan city was conquered by the Romans in 294 BC, by the consul Lucio Postumio Megello. The historian Tito Livio (X, 37, 3) thus remembers the conquest: the army was transferred to the territory of Roselle and here not only the countryside was devastated, but the city was also conquered; more than two thousand men were taken prisoner, a little less were killed around the walls.
In the 1st century AD, about three centuries after the Roman conquest, Roselle was affected by intense building and monumental activity, determined by the Augustan protection and the munificence of powerful local families. In the late imperial age it was subject to the decline that affected Roman cities and in the Middle Ages, despite being a bishopric, it was reduced to a modest center, with a smaller extension than that occupied by the Roman city, whose structures were often reused. In 1138 a bull of Pope Innocent II decreed the transfer of the diocese to the nearby center of Grosseto. From this moment Roselle was subject to a progressive abandonment and was reduced to … a wild solitude of stones and thorny bushes – the den of the fox and the wild boar, the snake and the lizard – visited only by the herdsman and the shepherd …, like the describes George Dennis, a 19th-century English diplomat and scholar, on the occasion of a visit to Maremma in search of Etruscan antiquities. The Archaeological Superintendence of Tuscany, from the 1960s to today, has continuously conducted research and restoration and enhancement interventions in Roselle.