The Thermes de Cluny are the ruins of Gallo-Roman thermal baths lying in the heart of Paris' 5th arrondissement, and which are partly subsumed into the Musée national du Moyen Âge - Thermes et hôtel de Cluny. The present bath ruins constitute about one-third of a massive bath complex that is believed to have been constructed around the beginning of the 3rd century. The best preserved room is the frigidarium, with intact architectural elements such as Gallo-Roman vaults, ribs and consoles, and fragments of original decorative wall painting and mosaics.