One of the distinctive features of the Pan American World Airways passenger terminal is its immense saucer-like roof. Over four acres in area, and large enough to cover Yankee Stadium, it hovers gracefully over the central terminal structure and extends out to protect jet planes and passengers from the weather. Basically, the elliptical-shaped roof is like a huge wagon wheel with 32 spokes. The hub is fixed by a central anchorage, but the actual support of the spokes is a series of heavy piers midway out to the rim. Two requirements were paramount when designing the roof: holding roof weight to the minimum (with accompanying savings in supporting structure and foundations); and achievement of sound absorption along with decorative potential. The first condition was met largely throughout the use of welded wire fabric for reinforcement of the 4 inch thick lightweight concrete slabs between the radial girders of the roof. A reduction in weight of reinforcement of about 20 percent was realized by the use of the fabric, due to its allowable tensile unit stress of 24,000 psi, compared to the 20,000 permitted for reinforcing bars. Other design provisions which affected dead load reductions included the use of lightweight aggregate concrete weighing 100 pounds per cubic foot and the specification of an acoustical cellular glass insulation in 3 inch thick blocks as the ceiling material. This material weighs only 2 pounds a square foot, is highly effective in reducing sound levels and is attractive when painted.