"American friends who flock to Paris in the summer months swear by this discreet Saint-Germain spa. A session in the Iyashi Dôme after a long-haul flight feels like a reset and somehow really helps with the jet lag. The long, tubelike structure is inspired by the Japanese purification ritual of burying oneself in the sands of hot springs and is said to stimulate the metabolism and accelerate the removal of toxins with infrared rays. The firming facials—using Carita products—help depuff dehydrated skin (so symptomatic of too much time up in the air). "