Those who can handle abrupt temperature changes can try the four room Nun Path, a variation of hot to cold with variations of humidity, a revival of a Roman regeneration treatment. (although only the most stalwart should attempt the Frigidarium.) And treatments span the globe, from hammam rituals to Thai and Ayurvedic.
FORBES: Taking The Waters In Italy, Part 2-A Designer Spa In A 13th Century Assisi Convent