10 Strange Ancient Puzzles That Are Still Stumping Scientists Today

For centuries, archaeologists have made discoveries that have left us amazed and confounded. While many of their breathtaking findings are located in Africa and what used to be Mesopotamia, many others have actually been found in the least likeliest of spots: America.

Despite being discovered in our own backyard, the origins of these ancient sites aren't always so clear. Just take these 10 mysterious and stunning North American archaeological finds that no one has been able to explain—yet. Each one is as strange as it is nearly inexplicable...

1. Great Serpent Mound: In Ohio, archaeologists discovered what came to be known as the Great Serpent Mound. The mound was constructed around 1000 AD and is in the shape of a giant snake. But what exactly is it?
Since then, no one has been able to determine who built the Great Serpent Mound or why, though some scholars believe it had been used as an effigy during sacrificial offerings or in religious ceremonies.
2. Lake Winnipesaukee mystery stone: The Lake Winnipesaukee mystery stone was discovered in New Hampshire in 1872. It features several symbols, including a face, ears of corn, and a teepee. What's so mysterious about it, though? Well...
It is still unknown who made it or why. There have been several theories, including that it was crafted as a gift from one tribe to another as part of some sort of peace treaty. Other theories have suggested it has Celtic or Inuit origins.