Ecologically minded architect Friedensreich Hundertwasser designed this compound’s central spa, living roofs, and buildings topped by onion domes. A portion of your bill goes to the World Wildlife Fund.

Rogner Bad Blumau, 43/(0) 33-835-1000, from $187 per person, including two meals. Photo courtesy of Rogner Bad Blumau. This appeared in the December/January 2010 issue.