Completed in 1976, the Sculpture consists of four concrete tunnels that are laid out on the desert floor in an open X configuration, 86 feet long on the diagonal. Each tunnel is 18 feet long and has an outside diameter of 9 feet, 2.5 inches and an inside diameter of 8 feet. The tunnels are aligned with each other and with the angles of the rising and setting of the sun on the days of the solstice, around June 21st and December 21st. On these days the sun is seen on the horizon centered through the tunnels.