Mysterious circles of megaliths (large, monumental stones) have intrigued us for millennia. These enigmatic and often elaborate stoneworks are scattered around the British Isles, parts of Europe, Africa and the Middle East. Some of them were built for ceremonial reasons, others as ancient markers or astronomical instruments. These landmarks were even put up for burials and social gatherings. Historians, though, aren't always certain why these age-old structures were erected by our ancestors, which only adds to their mystique.

Click through this gallery to see fascinating stone circles from around the world...