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Origin and history

The ancient baths of Alauna, located in Valognes in the Manche, constitute a Gallo-Roman thermal complex built in the second half of the first century (between 60 and 80). Disused in the third century, their masonries were recovered until the contemporary era. Their symmetrical plan, typical of the thermal baths of Nero, organizes around a central axis with cold and hot swimming pools, frigidarium, caldarium and sudatorium. The excavations of the 1990s made it possible to fully restore their plan before they were built into an archaeological garden.

The site, partially rising for 12 meters, is located to the northwest of the ancient agglomeration of Alauna, near the cardo maximus. Powered by an aqueduct of 800 meters, the complex used the local geological resources (calcareous, clay, sands) to build it. Its architecture optimised the natural topography, with warm parts placed below to limit excavations. The walls, thick from 1.20 to 2 meters, were built in opus vittatum (calcareous honeycombs) and architectural terracotta for the heating parts.

Protected by 1862, the thermal baths were identified as such at the end of the 17th century by Pierre-Joseph Dunod, after centuries of material recovery. The excavations of 1695, 1840 and 1990 revealed their internal organization, their heating systems (hypocaustes, praefurnia) and their decommissioning due to the decline of Alauna. In 2020, georadar prospecting identified potential additional buildings, such as a palester or mansio, suggesting a larger city (3,000 to 4,000 inhabitants).

The complex, the only known thermal establishment in Alauna, raises questions about its capacity for such a large population. Its symmetrical plan, with double rooms (apodyteria, unctoria, tepidaria), allowed for modulation of attendance and partial maintenance without total closure. The remains, among the rare Roman elevations preserved in Normandy with Lillebonne theatre, are now accessible in an archaeological garden open to the public.

The water supply, provided by an underground aqueduct becoming aerial near the thermal baths, ended in the sudatorium after a journey of 800 meters. Waste water was discharged to the Merderet via sculpins, including one belting the cold pool. The roof, extinct, was probably vaulted for the warm rooms, with a blanket "buried" in the exterior walls, as suggested by the high maintenance passages. The interior decorations, now unknown, were to include painted coatings or veneers, while the exteriors relied on alternating materials.

Ranked among the first French historical monuments (1862), the thermal baths survived the 1944 bombings. Their ongoing study reveals a more complex ancient city, with sanctuaries assumptions, a forum, and perhaps a second thermal complex near the cardo and the decumanus. Recent research, conducted by CNRS and INRAP, aims to clarify the extent of Alauna and its role in Gallo-Roman daily life.

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