Inaugurated in August 1902, the hydrotherapy institute was then considered a model of its kind. Open from May 15 to October 15, it can administer 1,200 treatments per day: baths, showers, massages, electrical and mechanical treatments. The architect Ernest Brunnarius designed a building of imposing dimensions (68 m by 25 m), surmounted by a dome of more than 30 m on a square base. Along the facade partially clad in earthenware, the ramps lead to a monumental entrance framed by bell towers. Under the porch, two paintings by Jean Benderly illustrate the theme of water. Listed as a Historic Monument, the building underwent a major renovation between 2004 and 2006. Renamed "Palais Lumière", it now houses a media library, exhibition halls and a convention centre.