Over 20,000 people gathered at Stonehenge in the U.K. on June 21 to witness the summer solstice sunrise, marking the Northern Hemisphere's longest day.

A new discovery near Stonehenge has revealed what archaeologists believe may be an early prototype for the monument’s solar alignment. It comes days before the solstice.

Dave Hamilton, author of a new guidebook to the weird and curious, shares some of the less-known places to celebrate the longest day of the year