Tschuggen Grand Hotel, Arosa, Graubünden; 41-81-378-9999; tschuggen.ch. There are 130 rooms, ranging from $385 to $2,450. Room 116, a single, is $385.

Is that the Aurora borealis outside your window? Not quite, though these man-made northern lights are just as magnetic. Perched atop Tschuggen Grand Hotel's new Bergoase Spa, the nine sail-shaped, glass-and-metal dormers illuminate the 43,000-square-foot minimalist facility, which comprises 12 treatment rooms, four indoor and outdoor pools, four sun terraces, and two spa suites, each with its own whirlpool and steam bath. Since opening in 1929, the Tschuggen Grand has been one of Switzerland's preeminent winter retreats, luring skiers, snowboarders, and even paragliders to Arosa's 37 miles of trails. However, few ventured here during the milder months (May through November), when the hotel was traditionally shuttered. That changed in 2006 with the opening of Swiss architect Mario Botta's modernist Bergoase Spa, which ushered in the Tschuggen Grand's first ever summer season. The spa's name, German for "mountain oasis," is certainly apt. Now, besides skis, golf clubs are the must-have accessory in Arosa, where you can tackle Europe's highest-altitude 18-hole golf course, a challenge at 6,560 feet. But after hitting the links, there's nothing like a nighttime view of those northern lights.