Every Veteran’s Day, for exactly one minute, this monument can be seen in its full glory.

Composed of five pillars, each representing an arm of the U.S. military, the monument’s shadows will align at precisely the right angles to form the great seal of the U.S. This isn’t just any day or hour: it was designed to do this at 11:11 every November 11th, or Veteran’s Day. According to its website:

“Additionally, the brick pavers within the Circle of Honor are inscribed with the names of U.S. servicemen and women, symbolizing the ‘support’ for the Armed Forces. The pavers are red, the pillars are white, and the sky is blue to represent America’s flag. The circle represents an unbreakable border.”

How did the engineers manage to calculate the rotational shadows down to the minute? The monument’s chief engineer Jim Martin says that they knew they had to create this with a “fixed azimuth (the horizontal angle from astronomical north to the center of the sun on Nov. 11 at 11:11 a.m. that creates the horizontal illumination of the Great Seal)” and a “fixed altitude angle (the vertical angle for zenith, or horizon, to the center of the sun on Nov. 11 at 11:11 a.m. that creates the vertical illumination of the Great Seal).” Even with the yearly variations, the monument is accurate—give or take, Martin writes on the website, 12 seconds.

The monument was designed by a local resident of Anthem named Renee Palmer-Jones. The pillars are quite high (tallest is 17 feet) and the order of the branches of the armed service were placed in accordance with Department of Defense protocol—United States Army, the United States Marine Corps, the United States Navy, the United States Air Force and the United States Coast Guard.

The monument itself is copyrighted, so it cannot be reproduced anywhere else.