10 U.S. Landmarks Whose Secrets Have Been Revealed And 10 That Are a Complete Mystery

There are a multitude of historic sites across the United States that are simply breathtaking. Some of them were even built before Europeans decided to set foot on this land. And thanks to research and the careful study of these sites, some of the mysteries behind these landmarks have been discovered. But others remain a complete and utter mystery that still baffle scientists.

Casa Grande Ruins

Photo by Greg Hume

The Casa Grande Ruins National Monument is located north of Coolidge, Arizona. The ancient building was reportedly built around 1350, and archaeologists believe that the ancient Sonoran Desert people are responsible for its construction. They lived in southern Arizona for about 1,000 years and built a network of irrigation canals to meet their agricultural needs.

They remained in this region until about 1450.

It’s One of the Biggest Mysteries of the Ancient World


And in 1694, an Italian Jesuit priest named Padre Eusebio Francisco Kino stumbled on the site. Casa Grande is made up of an aggregate stone called caliche and has remained unravaged by the passage of time for about 700 years. The site also shows evidence of the remains of other structures that surrounded Casa Grande.

But what was the purpose of building these unique structures? That remains an unsolved mystery, even today.

Georgia Guidestones

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The Georgia Guidestones are granite slabs that stand about 20 feet tall and emerged over Elbert County farmland in 1980. The monument contains six blocks that weigh a whopping 237,746 pounds. The stones have inscriptions with different declamations about limiting the world population to 500 million and a plea for fair laws and just courts.

The stones were commissioned by someone using the pseudonym Robert C. Christian from the Elberton Granite Finishing Company, and is engraved in eight different languages. Christian allegedly erected the structure because he wanted the monument to serve as a guideline for the human survivors of a future apocalypse.

Hemet Maze Stone

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The Hemet Maze Stone is located a couple of miles west of Helmet, California. Hike through the San Jacinto Valley and you’ll stumble on a huge boulder with a carved pattern that looks like a maze about two by two feet in size. It is said to be over 3,000 years old but it was only discovered in 1914.

The age of the Hemet Maze carving was determined by examining the encrustation that gathered on its surface over the years. But researchers have no idea who carved this maze or why.

Bighorn Medicine Wheel

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The Bighorn Medicine Wheel can be found in the Bighorn National Forest in Wyoming. It contains a circle made with white limestone rocks that expands across 80 feet and is displayed on the landscape with lines similar to a wheel’s spokes running from the center of the circle to its perimeter. This impressive landmark is believed to be over 10,000 years old and of Native American origin.

But while the site is considered sacred, it has no ties to a specific tribe.

No Tribes Have Claimed The Medicine Wheel

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In some Native American cultures, the medicine wheel is often associated to a variety of spiritual concepts. A 1972 study by an astronomer named John Eddy suggests that some of the cairns around the wheel’s perimeter align with celestial bodies as well as the summer solstice’s sunset and sunrise. But as to the purpose of the wheel, and why it was built in the first place, the world may never know as it remains a complete mystery.

Blythe Intaglios

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The Blythe Intaglios is approximately 13 miles north-east of Blythe, California, near Highway 95. Those who venture towards the Big Maria Mountains will find the Blythe Intaglios, which are large images etched into the rocky surface at the foot of the mountainous region. One of the largest is a human figure that’s 171 feet long.

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But there are other geoglyphs of mountain lions, birds and snakes as well as some unknown creatures and a few geometric patterns. The site was discovered by George Palmer in 1932 as his plane flew over it. There are six geoglyphs 1,000 feet from each other.

But no one has a clue as to what the images represent or who created them.

Judaculla Rock

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The Judaculla Rock is a massive soapstone rock with a flat side covered with mysterious etchings. It can be found near the banks of Caney Fork Creek in Jackson County, North Carolina. The soapstone contains etchings of 1,548 symbols and patterns like stick figures, deer tracks, a winged symbol and a circle surrounding a cross.

This mysterious and ancient boulder used to be a sacred site for the Cherokee Indians.

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Old folklore stories claim people have heard ghost sounds coming from the rock at night, which is extra scary, considering there’s a cemetery nearby. There’s evidence of extraction of materials, possibly to make bowls. Archaeologists believe the marks date back to the late Archaic era between 8,000 and 1,000 BC. The stone has a special place among the Cherokee tribe, and experts think the carvings represent different aspects of their world.

America’s Stonehenge

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America’s Stonehenge is located within the town boundaries of Salem and New Hampshire and bears a striking similarity to the Stonehenge in England. The site contains several large stones and boulders arranged into various structures. Experts believe that this site was erected by farmers at some point between the 18th and 19th century.

But some archaeologists think that William Goodwin, who bought the site in 1932, may have been responsible for the construction of Stonehenge.

Miami Circle

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The Miami Circle is located at the mouth of the Miami River in the downtown area of Miami, Florida, and is a perfectly carved circle made out of 600 post holes cleaved into limestone rock. The impressive circle is 38 feet across with 24 depressions cut into the rock. It was discovered during an archaeological survey shortly after an apartment building was demolished in 1998.

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Researchers used radio carbon dating of the wooden remnants to determine that the circles were about 1,800 to 2,000 years old. And while some experts believe the site was created by the Tequesta Tribe, others question its authenticity. But to this day, the purpose of this site remains a complete mystery.

The Great Serpent Mound

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The Great Serpent Mound can be found by the Ohio Brush Creek and is a curving that extend for 1,348 feet. When you see it from above, it looks like a gigantic snake. The mounds themselves are about one to three feet in height and about 25 feet across.

Experts believe it was built around 320 BC by the Adena people. But others believe that the people from the Fort Ancient Culture created the mounds in 1070 AD. To this day, the archaeological community is still debating who built the mound.

Mesa Verde Cliff Palace

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The Mesa Verde Cliff Palace contains a number of structures built into the rock formations in the Mesa Verde National Park. The Ancestral Puebloan people built the palace and lived in these buildings from about 1190 AD. But these people abandoned their homes in about 1300 AD for unknown reasons.

However, experts believe that climate changes, conflict with other tribes and over-population may have played a role in their decision to leave.

Waffle Rock


Waffle Rock Is a man-made reservoir located by the shores of Jennings Randolph Lake in Randolph County, West Virginia. The rock earned its name because of the unusual criss-cross line patterns which is similar to a waffle. And according to conspiracy theorists, the rock was made by aliens, while others believe giant lizards were involved.

But some believe that Native Americans are responsible for the marking. However, geologists believe that natural processes that began 300 million years ago are what caused the waffle-like patterns.

Spider Rock

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Spider Rock is located in Canyon de Chelly National Monument in Arizona, and looks like two towers that stretch up some 750 feet from the ground. The land it’s located on belongs to the Navajo people. And according to geologist Harold Pranger of the National Park Service, “Spider Rock at one time – many thousands to perhaps even hundreds of thousands of years – was connected to the ridge between the main Canyon de Chelly and Monument Canyon.”

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He also explained that, “The hillslope and stream erosion processes worked at different rates along that ridge, obviously at a slower rate right at Spider Rock. The differential erosion left this tower that is now called Spider Rock behind.”

Winnemucca Petroglyphs

Larry V. Benson, U.S. Geological Survey / {{PD-USGov-USGS}}

When the Winnemucca Lake dried up in the 1930s, it revealed the Winnemucca Petroglyphs, which are located in the north-west area of Nevada within the Pyramid Lake Indian Reservation.

A series of boulders at the western end of the lake bed revealed a series of ancient carvings of trees, flowers and a diamond design.

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The petroglyphs are about eight inches to three feet across. And radio carbon dating confirmed that the lake’s water level was low enough for humans to carve on the stones about 10,500 to 14,800 years ago. And although the meaning behind them is unknown, it’s considered North America’s most ancient discovered petroglyphs.

Cahokia Mounds State Historic Site


The Cahokia Mounds State Historic Site covers about 2,200 acres and contains about 80 separate mounds. It’s located across the Mississippi River from St. Louis and are the remains of an ancient city that may have covered a larger boundary of about 4,000 acres and included 120 mounds.

Sadly, the mounds that were built and occupied from about 1050 AD, are all that remains of a potentially powerful civilization. But evidence suggests the site was occupied as far back as 1200 BC. The remains suggest that the city contained a network of homes, ceremonial areas and public spaces. Modern researchers called the inhabitants Mississippians, but the site was abandoned in 1300 AD for unknown reasons.

Fort Mountain Wall

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Located in Georgia’s Fort Mountain State Park is the Fort Mountain Wall built with rough stone blocks. The wall zigzags and there’s also a tumbledown gateway at one point. Some stories suggest that the wall was built by a Welshman named Madoc who sailed to the United States in 1170 in built a couple of forts like this one.

But in 1956, University of Georgia archaeologists concluded that the wall was constructed by prehistoric aborigines. But no one has managed to figure out for sure who built it or why.

Aztalan Mounds

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The Aztalan Mounds are the remains of a great city dating back 1,000 years. This historical landmark is located in the Aztalan State Park in Jefferson County Wisconsin. It is believed that the Mississippians founded this city in 1000 AD, a civilization that stretched from the Great Lakes all the way to the Gulf Coast in those days.

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The mounds have a pyramid with a flat top and was undoubtedly used for ritualistic and defensive purposes. But the city reportedly started to decline around the 13th century and the inhabitants abandoned it. No one knows for sure why, but warfare and environmental issues may have played a role in their decision.

New England Stone Chambers

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The New England Stone Chambers are stone structures that some believe were built by the first European settlers in New England. The chambers were reportedly used as storage. But others believe that the stone chambers were built by Native Americans.

While both of these theories seem plausible, a third unlikely theory suggests that the structures were built by European travelers who journeyed to America during the Bronze age.

Chaco Canyon

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Chaco Canyon is at the core of New Mexico’s Chaco Culture National Historical Park. It’s also home to a number of Pre-Columbian buildings north of Mexico and contain 15 separate archaeological sites. According to experts, the buildings in the canyon were less likely dwellings and more likely ritual sites used by the Ancestral Puebloans from about 900 to 1150 AD.

Although the exact reason why the locals abandoned these sites is unclear, drought might have been to blame.

Poverty Point

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Poverty Point World Heritage Site is in the north-east side of Louisiana and includes earthworks in the form of ridges and mounds extending 345 acres around a large public space. The area’s structures were constructed around 1700 to 1100 BC.

Experts believe that the Poverty Point culture built these mounds about 3,700 years. But they have no idea whether the mounds were used for religious ceremonies or if they were a permanent city themselves.

Horseshoe Canyon

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Horseshoe Canyon is located in a remote area of Utah and is well known for its fascinating rock paintings. One of the best examples of pictographs are located in the area called the Great Gallery which displays a series of images painted in a style called Barrier Canyon. Researchers believe that the artists come from the nomadic hunter-gatherers of the Desert Archaic culture.

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Experts dated the pictographs between 400 and 1100 AD, but evidence of Paleo-Indian presence in the Horseshoe Canyon dates back as far as 9000 BC. So, some believe that the images found in the Great Gallery may be around 7,000 years old. But the meaning behind the images or their exact date is a total enigma.