The hot springs () were known since the Roman period, when the town was Aquae Flaviae; the "Waters of Flavius" were an important social gathering point, but fell into disuse as the town was slowly abandoned by attacks. The spas belong to a vast area of hydrothermal springs that stretch from Verín (in Galicia) to Pedras Salgadas, 30 km from Chaves (on the road to Vila Real). Despite its vastness and abundance of water, this thermal system is little utilized; of the nine groups of thermal springs there are only adequate installations in four of them: Chaves, Carvalhelhos, Vidago, Pedras Salgadas, and Verín. The waters of the spring, that are captured in three springs within Chaves, have mean temperatures of (the hottest bicarbonate waters in Europe). The modern spa industry in Chaves use these waters for numerous treatments, including stomach, liver, intestinal, and kidney ailments, through oral ingestion. Many small guesthouses in the old part of the town are dependent on the influx of these visitors. The thermal spas are located between the castle and the river, in front of a large area of grass-covered park with playgrounds and tennis courts.