The Friedrichsbad is the grand 19th-century bathhouse that defines Baden-Baden's claim to be a spa town. Opened in 1877, it pioneered the Roman-Irish bathing tradition — a seventeen-step ritual of dry saunas, steam rooms, thermal pools, scrubs, and rest periods that runs about three hours. Clothing is removed in the changing room and not put back on until the end; the bathing days are mostly mixed.
The building itself is the other attraction: a domed central hall of pale marble, mosaic floors, and frescoed ceilings that would not be out of place in an opera house. Take your time, follow the numbered stations, and emerge several centimetres taller than you went in. Bring nothing — towels and slippers are provided. Children under 14 are not admitted.