Above the crossing is a domed roof, which was meant as a temporary covering until the tower above the crossing was built. It was completed within fifteen weeks between May and August 1909. The dome is shaped like a saucer, and consists of several overlapping layers of Guastavino tile, which support themselves around the dome's center upon their own weight. The pendentives, or triangular areas between the circular dome and the corners of the arches, are thick; the thickness of the dome itself ranges from on top to at the bottom. Compared to conventional ceilings, the tiles saved money because they did not require temporary supports when they were installed. For added strength, metal rods were included in the dome's shell.
