Sun Tunnels

In 1976, the American artist Nancy Holt completed this large piece of art consisting of four concrete tubes laid out in an open X configuration in Utah's Great Basin Desert.

The piece is called Sun Tunnels, and its deceptively simple design allows for constant changes in light and shadow. According to Holt, the artwork is meant to "bring the vast space of the desert back to human scale." 

At first, the four concrete tunnels pierced by holes of varying sizes may seem like minimalist modern art, but the work is in fact much more than that. It is an astrological gazing station. Each of the 18-foot long cylinders represents one of four constellations: Draco, Perseus, Columba, and Capricorn. The smaller holes drilled into the sides of the tunnels depict the pattern of stars that make up each constellation.

At the summer and winter solstices, on June 21 and December 21, respectively, the sun can be seen on the horizon centered through the tunnels. Two of the tunnels are aligned to the sunrise, while the other two are aligned to the sunset. The holes drilled in the sides of the tunnels allow patterns of light inside, so during the day, you can see the shape of the referenced constellations.