The ancient city of Roselle stood on an elliptical hill, comprising two hills separated by a central valley. This site was the hub of the community's political and religious life through the centuries. The Etruscans, in the 7th century BC, carefully decided to urbanize this area. The choice was not random; the elevated position allowed a natural defense of the place and the control of the Grosseto plain, previously occupied by Lake Prile, a vast lagoon communicating with the sea. The Etruscan city was conquered by the Romans in 294 BC, under the command of the consul Lucius Postumius Megello. This conquest is described in history by Titus Livy (X, 37, 3). In the 1st century AD, approximately three centuries after the Roman conquest, Roselle underwent an important phase of building and monumental activity, a period that benefited from Augustan protection and the generosity of influential local families. In the late imperial age, it suffered the decline common to Roman cities. In the Middle Ages, although it retained the status of a bishopric, Roselle shrank considerably, with a smaller surface area than in Roman times, and often reused the ancient structures. In 1138, a bull from Pope Innocent II established the transfer of the diocese to the nearby center of Grosseto. From that moment, Roselle began to suffer progressive abandonment and became a wild place, as described by George Dennis, a 19th century English diplomat and scholar, during his search for Etruscan antiquities.