Sheik Schussing
Ski Dubai, United Arab Emirates
Opened: December 2005
THE CHALLENGE: Build a 280-foot ice-capped mountain in a flat desert where temperatures reach 120 degrees. To pull it off, workers constructed a 25-story refrigerator with 16-foot-thick insulation inside a complex that could house three football fields. Instead of using traditional snowmaking equipment, Ski Dubai creates real flakes by seeding an atomized water cloud with ten-micron ice particles—generating 30 tons of fluff a day.
THE PAYOFF: Besides real snow, Ski Dubai claims "the world's first indoor black diamond run," at 35 degrees, while the longest trail drops 200 feet over a gentle quarter-mile. There's a lodge, lifts, and evergreens, but, alas, no blue-sky days. $35 for equipment and two hours of skiing; www.skidxb.com

Crank House
Ray's MTB Indoor Park, Cleveland, Ohio
Opened: November 2004
THE CHALLENGE: Use 20 tons of stone and five houses' worth of wood to construct more than a mile of mountain-bike trails, tracks, and jumps inside a retired 71,000-square-foot Army parachute factory.
THE PAYOFF: Challenging urban singletrack, a foam pit for practicing flips, a dozen berms, 20 jumps, and a halfpipe—all close enough for Clevelanders to catch on the way home from work. $18 for a day pass, armor, and access to a fleet of demo bikes; www.raysmtb.com