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. 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.

Magnus Manske / Wikimedia Commons

2. Native American cave petroglyphs: During the 19th century, a small cave in West Virginia was discovered. What was unusual, however, was that the walls inside were covered with petroglyphs of animals like fish and snakes…

One of the more curious aspects of these carvings was the presence of a “red coloring matter,” which was seen in several of the etchings. It has since been confirmed to be the work of a Native American tribe, though which one exactly has yet to be determined.

3. America’s Stonehenge: Made up of exquisite stone chambers, rock structures, and walls, what came to be known as “America’s Stonehenge” is believed to be an ancient settlement in Salem, New Hampshire.

There are several different theories surrounding the mysterious structure. The most commonly believed theory attributes it to an ancient Native American tribe, which likely used it for religious ceremonies more than 2,000 years ago.

4. Poverty Point: This extensive complex of earthworks is located in Louisiana. It was entirely made up of a series of manmade mounds and remains one of the few known complex sites of its kind credited to a hunter-gatherer society. There’s just one issue with it, though…

No one is entirely sure what Poverty Point’s original intended purpose was! However, some archaeologists believe it may have been a place for ceremonial events hosted by the local inhabitants.

Billy Hathorn / Wikimedia Commons

5. The Upton Chamber Cave: This cave was constructed into a hill in Massachusetts and consists of a long passageway that opens up into a dome. The workmanship of the chamber indicates that whomever built it had a working knowledge of stonework. But what makes it so special?

Amazingly, this structure is also astronomically aligned. According to researchers, the entrance to the chamber aligns perfectly with the sun on the day of the summer solstice. How cool is that?

6. 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.

7. Petroglyphs of Winnemucca Lake: Modern-day archaeologists believe that Winnemucca Lake in Nevada contains the oldest petroglyphs in the entirety of the continent of North America.

These archaeologists believe that the ancient petroglyphs are, roughly speaking, as much as 10,000 years old. However, they still don’t know the particular meaning of any of the carvings to this day!

8. Cahokia: Boasting a population of nearly 15,000 people, Cahokia was, at one point, the largest city in pre-Columbian North America. It was settled between 700 and 1300 AD, and it had its own ruling class and unique culture.

The people of Cahokia were farmers, partook in battles with other tribes, and legend has it, practiced human sacrifice. One day, out of the blue, they vanished from the territory, and their subsequent whereabouts have baffled historians for ages.

9. The Maine Penny: In 1957, archaeologists discovered the Maine Penny buried in the dirt while excavating a former Native American settlement. It has been confirmed to be the only pre-Columbian Norse artifact ever discovered in the United States.

The experts originally believed the penny to be of British descent from the 12th century, though this was later disproven. Other researchers suggested the Viking coin was originally minted between 1065 and 1080 and was brought to North America during the 12th century.

10. Dighton Rock: Found in the Taunton River in Massachusetts, Dighton Rock is a gigantic, 40-ton boulder containing mysterious markings. The markings, however, don’t seem to have any recognizable style and have led to debates among researchers…

Some have theorized that the mysterious markings may have Norse, Chinese, or Native American backgrounds. Even still, none of these suggestions have ever been confirmed.

These discoveries are so amazing that it almost doesn’t matter if we never learn what they are. Sometimes, a little mystery is nice!

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