Spas with steam room

Boston, Massachusetts

A Finnish kelo-log banya in Newton with sauna, steam room and cold plunge, alternating men's and women's days, day passes from $69.

Chicago, Illinois

A 24-hour Korean bathhouse and sauna complex in Niles near Chicago, with 11 heat rooms, hot and cold pools, and a $45 day pass covering walk-in access.

Tuscany

A five-star resort in the Tuscan countryside built around a natural thermal spring, with day passes from €39 for outdoor thermal pools, hydromassage circuits