Though its historic ruins are generally less ancient and fewer in number than they are in other parts of the world, America is littered with hundreds of ancient sites, and some of them are well over a thousand years old.
Many are in states like Arizona, Colorado, Utah and New Mexico, but there are others in the Midwest, Northeast, and Gulf Coast regions as well.
It’s often the most monumental structures found in the Southwest that are the most studied and well preserved, but as we’ll see, some lesser known ruins thousands of miles away are just as impressive and intriguing.
1. Chaco Canyon, New Mexico
Spread over nearly 34,000 acres and consisting of 4,000 individual archaeological sites, Chaco Canyon in northwestern New Mexico’s San Juan Basin is one of the country’s most expansive ancient ruins.
Once home to pre-Columbian Pueblo people called Anasazi, or “Ancient Ones,” Chaco’s residents eked out a living for thousands of years in particularly harsh high desert terrain known for hot dry weather in the summer and biting cold in the winter.
For much of their existence the Pueblo led nomadic hunter-gatherer existences, but beginning in about the second century AD they began building small pit houses and cultivating crops like gourds, beans and corn.
Yet by the time Spanish explorers and missionaries began arriving in the 1600s Chaco had been abandoned for hundreds of years.
Archaeologists believe that by the middle of the 9th century Chaco had reached its apex as a regional hub of trade, ceremony and politics that may have dominated the Four Corners region including portions of Colorado, Arizona, New Mexico and Utah.
Though original buildings were relatively small, over the centuries the Pueblo built increasingly large multi-story structures along a nearly 10-mile stretch of canyon that towered dozens of meters over the desert floor below and included more than 500 individual rooms, making them the largest buildings in North America until the 1800s.
Connected by paths and roads, and with unobstructed lines of sight between them to facilitate communication, these great homes were truly remarkable feats of engineering.
In addition, many of Chaco’s buildings were aligned with important celestial cycles that astronomers believe may have taken generations to plot.
The structures also included water collection systems and abundant storage from which archaeologists conclude that central planning and extensive trade networks were prevalent.
In fact excavations have uncovered items not naturally found in the area like parrot feathers, shells, copper trinkets, and chocolate residue that probably came from modern day Mexico.
Chaco Canyon is also brimming with circular ceremonial structures called kivas, the largest of which measure more than 60 feet (19 m) in diameter and are found in nine distinct complexes in the site’s central area.
Kivas were partially excavated from the porous ground below, ringed by thick stone walls, and are thought to have been holy places where ceremonies were held and oral traditions passed from one generation to the next.
It’s estimated that as many as 5,000 people resided in the canyon at its height, though by the 12th century it was nearly entirely abandoned, most likely due to a multi-decade drought that’d begun years earlier making water increasingly scarce.
After abandoning the site the Pueblo probably migrated to settlements in neighboring states that experienced significant population growth around the same time.
As far back as the late 1800s many of Chaco’s structures had fallen into dire disrepair from looting, vandalism and the ravages of time and the elements, which led to its establishment as Chaco Canyon National Monument in 1907, and later as a UNESCO World Heritage Site in 1987.
2. Cahokia Mounds, Illinois
Archaeologists believe the Mississipian civilization that once flourished at Cahokia Mounds was among the most advanced of its time, and that in the mid-12th century its estimated population of nearly 40,000 was larger than London’s.
Cahokia’s ideal location near the confluence of the Missouri, Illinois and Mississippi Rivers was key to its ascension as a powerhouse of trade, education and concentrated political power that may have extended north to the Great Lakes and south to the Gulf Coast.
The site was probably intermittently occupied as early as 1200 BC, though the mounds weren’t built until much later when occupation became permanent, probably between 800 and 1400 AD.
The Native Americans who settled in the area were largely drawn by its fertile, easily tillable soil that was more suitable to growing corn than the nearby prairie since Cahokians lacked both plows and beasts of burden like oxen.
In total the Cahokia site sprawls across nearly 4,000 acres (1,600 ha) and includes more than 120 individual mounds, the most prominent of which is Monks Mound, one of the largest prehistoric earthworks in the New World.
Monks Mound is located in the upper-central portion of the site, has a footprint of more than 12 acres (5 ha), stands nearly 100 feet (30 m) high, and is generally believed to have been the site’s ceremonial center and possibly the residence of the civilization’s highest ranking official.
Most of the smaller mounds alternately served as foundations for public buildings and burial mounds known as tumuli, and though most are circular, others are more rectangular.
Their distribution across the site seems random, but some researchers see clear evidence that the mounds were intentionally placed in relation to significant celestial events like the summer and winter solstices.
The site is also famous for its large observatory known as Woodhenge which was built with wooden posts forming concentric circles, the largest of which – Woodhenge V – has a diameter of nearly 500 feet (152 m).
Woodhenge is similar to Stonehenge in the United Kingdom in many respects, and was probably used primarily for predicting important agricultural cycles.
In another outlying mound referred to as Mound 72, archaeologists uncovered remains of a prominent figure in Cahokian society who they nicknamed “Birdman,” because he was buried with a small sandstone tablet inscribed with a man in costume resembling a bird of prey like an eagle or falcon, both of which represented wisdom and virility in Mississipian culture.
Other figures were also interred in various mounds, and evidence suggests that some may have been buried alive, perhaps as ritual sacrifices to ensure bountiful crops, fish and game in the coming year.
Of the original mounds only about 80 remain, and Cahokia is one of only a few dozen UNESCO World Heritage sites in the United States.
3. Bighorn Medicine Wheel, Wyoming
Resting nearly 10,000 feet above sea level atop Medicine Mountain in north-central Wyoming’s Bighorn Range, a massive 75-foot stone “Medicine Wheel” lies covered in snow for much of the year.
The spring thaw comes late in Wyoming, but when the snow does finally melt away it reveals the largest and most well-preserved Native American structure of its kind in North America.
Also referred to as sacred hoops, hundreds of medicine wheels were built by Native North Americans for nearly 1,000 years, and they’re found in the Dakotas, Montana, Alberta and Saskatchewan.
Tests like radiocarbon dating aren’t useful in determining the wheel’s age since the individual rocks used in its construction are exponentially older than the wheel itself, but it’s believed that Bighorn was built by the Plains tribes between 300 and 800 years ago.
The wheel was constructed with locally gathered rocks, has a circumference of nearly 250 feet, and consists of 28 spokes more than 35 feet long, each of which radiates outward from an 8-foot diameter central cairn, or rock circle, which experts agree is precisely where its true significance and meaning are revealed.
The number 28 is sacred among many Native American tribes due to its association with lunar cycles, and it’s found throughout their dwellings, artwork and oral traditions.
When sitting or standing in the central cairn, vision is naturally drawn to two points on the distant horizon which are where the sun rises and sets on the summer solstice, the longest day of the year.
In addition to a number of other significant celestial markers, the Crow people who lived in the region for generations associate the medicine wheel with the face of a mythical boy called Burnt Face, who had his face disfigured after falling into a fire as a child.
According to legend, Burnt Face built the wheel while on a vision quest in his early teens, and subsequently had his facial damage reversed after slaying a beast responsible for systematically killing young eagles.
In recent decades medicine wheels have been adopted as symbols of nature and holistic healing by Pagans, New Age gurus and non-denominational spiritualists, and visitors are just as commonly tai dai-clad hippies as reverent Native Americans.
Especially in the late 1800s and early 1900s, Bighorn Medicine Wheel became an ever more poignant symbol of wisdom and connection for Native American chiefs from all over the region who made pilgrimages to pray for guidance at times when their people were being hunted, exterminated, and forced to give up their traditional lands and lifestyles for meager reservation existences.
The medicine wheel was added to the National Register of Historic Places in 1969, and is still an accurate predictor of the summer solstice.
4. Serpent Mound, Ohio
Stretching nearly 1,400 feet (410 meters) across an exposed hilltop near Peebles, Ohio, an ancient earthwork in the form of a serpent has remained a mystery to historians and archaeologists since it was discovered in the mid-1800s.
Known as an effigy mound for its animal depiction, the historic landmark may have been built by the Adena culture that lived in the area for nearly 1,000 years, but though the site has been partially excavated numerous times over the years, its lack of artifacts and remains have made definitively assigning it to one particular culture nearly impossible.
The Adena were pre-Columbian Native Americans who lived in parts of Ohio, West Virginia, Indiana and Kentucky between the 9th century BC and the end of the first century AD, and were among the first North Americans to transition from a hunter-gatherer existence to permanent settlements and farming.
But the Adena theory was turned on its head in the early ‘90s when radiocarbon dating determined that the mound was approximately 900-year-old, suggesting that it was built by the later Fort Ancient culture around 1000 AD.
Though the serpent’s length makes it the largest effigy of its kind in the world, it’s just 5 feet higher than the surrounding ground and about 20 feet wide at its widest point, and ironically, it’s most clearly visible from the sky – a vantage point from which the ancient people who created it wouldn’t have had the luxury of viewing it.
At first glance the serpent’s gaping mouth appears poised to devour a large egg much wider than its body, but on the other side of the egg there’s another nearly identical mouth.
Some interpretations claim it’s two snakes, while others suggest that the second isn’t a snake at all, but the other side of the first snake’s head, and that the egg isn’t an egg, but a large oval eye.
Either way, in Ohioan culture snakes were believed to have supernatural powers, but no one really knows why it was built or what it symbolizes.
Adding to the mystery, the serpent mound lies inside an 8-mile wide crater formed when a meteor crashed into the earth more than 300 million years ago, which may have been intentional or merely a coincidence.
In 2008, Serpent Mound was included on a list of sites submitted by the US Department of the Interior to be recognized as a UNESCO World Heritage Site, though it’ll likely be at least 2023 when it’s either accepted or rejected.
5. Mesa Verde Cliff Dwellings, Colorado
Thanks largely to their remoteness, sturdy construction, and the area’s arid environment, Southeast Colorado’s Mesa Verde cliff dwellings are among the most well-preserved ancient ruins in North America.
Located deep within Mesa Verde National Park, the ruins remained undiscovered to non-Native Americans until the late 1880’s when they were found by local ranchers rounding up stray cattle.
Also known as the Anasazi, the ancestral Pueblo people who built the dwellings probably lived in the area for generations before construction began around 1100 AD, but for the previous 600 years they lived on top of the mesa as opposed to under its more sheltered and defensible cliffs.
The epic construction project ultimately resulted in hundreds of residences, public areas, storage rooms and circular ceremonial kivas built from sandstone, mortar and timber, but considering its abundant structures the civilization had a relatively small population, most likely due to scarce food and water.
The park’s Cliff Palace is the largest cliff dwelling structure in the United States, but though it’s purported to be 800-years-old, evidence suggests that it was occupied for a relatively short time period before being entirely abandoned in about 1300 AD.
Despite its name, conditions in the Cliff Palace were far from extravagant, though living in permanent structures was relatively new and safe, and provided protection from the elements that the resident’s hunter-gatherer ancestors probably never enjoyed.
Another of the site’s largest structures is Balcony House comprising more than 3 dozen rooms and kivas, but though it was fed water by a fresh spring for much of the year, it too was probably home to no more than 30 residents.
Ironically, many of the buildings received precious little sunlight which would’ve helped keep them relatively cool in the summer, but made them unthinkably cold in the winter.
Long House is another of the park’s most notable attractions, and was excavated and stabilized in the 1950s and ‘60s.
It features 150 rooms, more than 20 kivas, a number of dedicated storage rooms and may have been home to nearly 200 people.
Long House probably functioned both as a residence, public area for community gatherings and events, as well as a market where traders from near and far bought and sold their wares.
By the late 1270s Mesa Verde’s population began migrating south into present-day New Mexico and Arizona, and just a few decades later the site was totally abandoned.