Tokyo's Roppongi Hills is taking the concept of the observation deck to a new level: the roof. As of Saturday, the open-air Sky Deck will be inaugurated atop the 52-story Roppongi Hills Mori Tower. At 238 meters above ground level, and 270 meters above sea level, it will be the highest open-air facility in Japan.

Roppongi Hills, which this month celebrates the fifth anniversary of its opening, has always had an indoor observation deck, its 52nd-floor Tokyo City View whose huge windows offer stunning views of the metropolis below.

Few longtime residents will forget the shock of looking down on Tokyo Tower for the first time.

The new Sky Deck, built around the rim of the rooftop heliport, represents a significant step up.

Imagine looking up to see your your first-ever completely unobstructed view of the sky over Tokyo. Close your eyes and feel the wind that is normally reserved for the crows and chopper crews — and which is often surprisingly calm.

The wooden deck, set safely back several meters from the edge, is accessible from inside Tokyo City View. Admission is included in that facility's ¥1,500 entrance fee.

Details at: www.roppongihills.com/tcv/