Stonehenge at Twilight, England

Photograph by Ken Geiger, National Geographic Staff

Lights in nearby Amesbury set low-hanging clouds aglow, and the standing stones turn otherworldly beneath a burning sky. But their surfaces bear witness to homely labor: Topping the tallest stone, once part of a trilithon, is a tenon—half of a mortise-and-tenon joint borrowed from woodworking.