Roughly 5,000 years ago, ancient inhabitants of the British Isles somehow dragged as many as 40 giant stones—the heaviest weighing an estimated 16 tons—onto this grassy plateau in what is now England"s Lake District National Park in Cumbria. They then grouped them into the stone circle at Castlerigg, seen here casting shadows from the low winter sun. Archeologists believe stone circles were arranged to align with solar and lunar positions. They were used in elaborate rituals to celebrate occasions like today"s winter solstice, the shortest day (and longest night) of the year in the Northern Hemisphere.