There are many reasons to celebrate the spring equinox. For one, it's the time when days start getting longer than nights.
For millennia, people all over the world have marked this mystical occasion, which often symbolizes the beginning of spring or a time of rebirth.
Archaeologists have found many ancient sites that line up with the equinox. But the purpose of these sites often remains shrouded in mystery.
As the spring equinox is around the corner — at 17:24 ET on March 20 — we look at 11 sites that line up with the equinox, and what experts think about them.