Bennett Monolith Tiwanaku Archaeological Site, Bolivia

It's hard to tell the scale of this weathered statue—is it life-size or a few stories high? In fact, it's in between, standing a little over 11 feet tall. Covered in intricate carved symbols, monoliths like this are found throughout Tiwanaku, a longstanding archaeological site in western Bolivia. But they're not scattered at random. The pre-Columbian society that lived here—founded at least 1,900 years ago—believed this was the center of the universe, and the site's key monuments align to the sun's path during equinoxes and solstices. Just how many people lived here (some say over 20,000), what language they spoke (leading theories posit Puquina), and whom their statues depict (possibly a mythic race of stone giants) are all still mysteries. But the search for clues continues: Aided by modern tech like drone photography, researchers have found new structures here as recently as 2016.