The Vegas World Stratosphere Tower, a reinforced concrete observation tower soaring 1,102 feet over Las Vegas is the tallest structure of its kind in the US.

Complex in design, the Stratosphere is actually 5 separate structures. At its center is a hexagonal shaped concrete tower with 20-foot-wide walls positioned on a concrete foundation. Around this central tower at 120-degree intervals are three 20x32-foot rectangular bracing legs that incline toward the tower. At 260 feet above ground level, the legs intercept the central tower and the four elements join to form a single 112-foot-diameter section. As the legs climb to their total height of 800 feet, they gradually incline outward to cradle the Stratosphere's top structure - a 12-story, 145-foot-diameter pod.

Leeman Corp., Las Vegas, the project's general contractor, decided to use custom-designed self-climbing gang forms to speed construction and reduce labor requirements. Using the self-lifting systems, Leeman could pour 11-foot, 8-inch lifts and complete about two floors a week.