The baths at Bagni di Roselle were built between the late 1st century and the early 2nd century A.D. in the _suburbia_ of Roselle, ancient Roman colony now situated within the territory of Grosseto. The continuous occupation of the area has caused the destruction of most of the settlement. The site’s history has been reconstructed using the descriptions of the 19th century excavations, an analysis of the standing walled structures and a number of trenches dug by the Superintendency of Tuscany. The baths were built on an ancient hot water spring that is still active today, although not used. The position on an important secondary road, linking Roselle with its ports on the Tyrrhenian coast, also made the settlement an important stopping place. The elegance of the construction and other archaeological evidence suggest that the structure was part of the imperial property between the late 1st and early 2nd century A.D. This was an act of evergetism on the part of the emperor, new owner of all or part of the _ager_ _Rusellanus_, who in the same years perhaps donated the public baths to the colony of Roselle. Several tile stamps make it possible to attribute the construction to Trajan. The building of the baths at Bagni di Roselle was part of a great project for the reorganisation of the territory between Roselle and Cosa, acquired by the _res_ _Caesaris_, which also involved the roads and ports. The roads were restructured and new way-stations were built, including that at Bagno di Roselle in the city’s _suburbio_. The toponym Aquae Rusellanae, mentioned by Clüver (III), derives from the therapeutic properties of the hot springs on which the baths were built, repeatedly mentioned in the Medieval period. Evidence relating to the Medieval occupation of the site is scarce. The ruins of the Roman settlement, abandoned by the end of the 4th century A.D., were occupied by a cemetery that can be generically dated to the Medieval period. The early Medieval period is documented by the presence of a new bath building that partially incorporated the Roman one, today known as the Terme Leopoldine after the reconstruction between 1822 and 1824 carried out by Ferdinando III of Lorraine.