If you have a fear of heights, then "Step Into the Void" is essentially your nightmare come to life. The tourist attraction, which opened yesterday, is essentially a glass cube suspended at the top of the Aiguille du Midi, a 12,605-foot tall peak in the French Alps. What's below: a 3,280-foot drop. It's being plugged as the tallest attraction on the continent, and the Independent notes that visitors are to treat it with care: They're asked to don slippers while in the box to protect the glass. A French tourism company is behind the attraction, which has been three years in the making and features five transparent sides made of three layers of tempered glass fixed with metal to a big support structure, reports the AP. Viewable from it: Mont Blanc.