Castilla Termal Brihuega

From a distance, the circular stone walls read more like a bullring than a hotel, and the mix-up is forgivable. The 18th-century textile factory outside Madrid is now a wellness-focused luxury hotel, its two concentric rings arranged around a courtyard, with high-ceilinged rooms showing original beams and a glass-domed restaurant lit by lanterns at night. The stone spa and thermal baths do most of the heavy lifting for guests who came specifically to do nothing.