A 26,000-Year Astronomical Monument Hidden in Plain Sight

The plaza’s terrazzo floor is actually a celestial map that marks the time of the dam’s creation based on the 25,772-year axial precession of the earth. In order to understand how the plaza marks the date of the dam’s construction in the nearly 26,000-year cycle of the earth’s precession, it is worth explaining what exactly axial precession is. I would like to thank Emme Woodward of the US Bureau of Reclamation for all her help in finding the original images and plans of Monument Plaza.

Source: blog.longnow.org