Sun Tunnels is an artwork by Nancy Holt, completed in 1976, consisting of four large concrete tubes, laid out in the desert in an open X configuration. The nine foot diameter, 18 foot-long tunnels are pierced by holes of varying size that correspond with the pattern of selected celestial constellations. There is a tunnel for Draco, Perseus, Columba and Capricorn. The tunnels line up with the rising and falling sun of the summer and winter solstices.