The four legs were erected first, followed by the cantilevers.[17] The first elevated floor is supported on the legs' 19.7' deep bottom chords, while a second set of chords supports the other floors.[17] Each of the four composite steel with reinforced concrete legs is a 46' deep "H" shape.[17] From the plaza to the first raised floor, they are 63' tall.[17] The building is cantilevered 119' over the legs on the North and South sides.[17] Fluorine resin-coated square panels cover the building.[20] To protect the artifacts from vibrations and earthquakes, 126 springs are positioned throughout the overhang capable of absorbing 3.5 inches of vertical movement.[