Ancient Rome's passion for thermal waters extended to the far reaches of their empire, and an important neighbouring province such as Sardinia could not be missed. On the island they built their main baths in Fordongianus, to capitalise on waters that rise to the surface very hot (at 54 degrees) while maintaining their beneficial properties.

However, the history of thermal baths here, as in many other island spas, is much older, dating back to prehistoric times: the pre-nuragic and nuragic Sardinians considered these waters sacred and used them to heal themselves. Sacred springs and wells probably attracted the early Sardinian populations from other island territories near and far. In fact, the plains around the town today are dotted with prehistoric settlements, including Casteddu ecciu and several domus de Janas necropolises.

The Roman thermal complex was built on the banks of the River Tirso, precisely on the site of Caddas (appropriately meaning 'hot') that the Romans called aquae ypsitanae. Emperor Trajan commissioned the establishment at the edge of the town centre of Forum Traiani, the great trading market between the Romanised populations of the hinterland behind the Gulf of Oristano and the communities of the north and south of the island. When the complex was built, the forum also became a place of wellbeing and a social gathering place, where people not only bathed in the pools but also strolled along the arcades around the pools discussing politics and business: Forum Traiani became a popular destination for cultivating physical and mental health and the pleasures of life. The architecture, with its arcades, halls and pools, is still impressive today and gives an idea of what it must have been like in the days of imperial Rome.

In the centre of the establishment is a large rectangular pool reserved for bathing in warm water (tepidarium), once covered with a barrel vault and surrounded by porticoes where people stopped and rested between baths. On either side are the catchment and mixing basins and the Nymphaeum, a large basin surrounded by niches where statues and votive plaques were displayed. This was the sacred space for the worship of the healing powers of the aquae calidae. More secluded is the thermal pool circuit, from the hot baths (calidaria) to the frigidarium with changing rooms and dining areas.

Private patrician houses, 'reception facilities' for visitors, public buildings for civil activities and funerary rites were built around the spa, most of which are now part of the subsoil of the town of Fordongianus, which shows signs of ancient remains in many parts of its urban grid. With the fall of the Roman Empire, the baths were gradually abandoned. The final blow came during the Middle Ages, when they were dismantled to build churches, convents and places of worship. The strictly therapeutic parts of the building were saved, along with a few others that escaped the new worldview, but were fortunate enough to continue the tradition of the thermal baths and still make the former Forum Traiani a wellness centre par excellence.