Nancy Holt, an artist exploring the human perception of time and space, earth and sky, built the Solar Tunnels as a unique artistic project completed in 1976. The four tunnels are concrete tubes arranged in the shape of X, each pierced with holes to model the constellations of Draco, Perseus, Columbia, and Capricorn. They are massive - nine feet high by 18 feet long. They sit in a valley west of the Bonneville Salt Flats. Holt said her tunnels bring the sky down to earth with the dazzling effect of the light bouncing through the tubes.