Hoover Dam’s Zodiac Compass (1938)

The Zodiac Compass at Hoover Dam

Set into the terrazzo floor of Monument Plaza at Hoover Dam, the zodiac compass is a directional marker designed by Oskar J.W. Hansen. It shows the cardinal directions, marks the dam’s geographic coordinates, and surrounds the compass points with zodiac symbols.

The compass works with the star map set into the same plaza floor. Where the star map tracks 26,000 years of precession, the compass anchors the site to a specific place on Earth. Together, they give the plaza both a cosmic and geographic orientation.

The terrazzo inlay is part of Hansen’s sculptural program at Hoover Dam, completed in 1938.

Design and Materials

Hansen used terrazzo inlay for the compass, matching the star map material. The zodiac symbols around the compass rose are traditional Western astrological figures. The compass marks true north, not magnetic north.

What the Zodiac Symbols Mean

The zodiac symbols serve a practical purpose here. They divide the compass into twelve segments corresponding to the twelve houses of the zodiac, which are tied to the sun’s apparent path across the sky. This connects the compass to the star map’s astronomical function. It’s navigation, not astrology.

Visiting the Zodiac Compass

The zodiac compass is set into the plaza floor between the Winged Figures of the Republic. It’s underfoot and easy to miss if you’re not looking for it. Accessible during standard Hoover Dam visits.