Sacsayhuaman, the Inca's largest structure

Machu Picchu explained

High in the Andes Mountains, Machu Picchu stands as a testament to the ingenuity and resilience of the Inca Empire. Constructed in the mid-15th century during Emperor Pachacuti’s reign, this site is believed to have served as a royal retreat or ceremonial center. Its engineering marvels, including sophisticated aqueducts, terraced farming systems, and precisely carved stone structures like the Sun Temple, highlight the advanced skills of the Inca civilization.

Scientists are still confused how Machu Picchu was built

Machu Picchu, the 15th-century Inca city high in the Andes, continues to fascinate experts with its mysteries. The methods used to transport and carve its massive stones—some weighing 15 tons—remain unclear. Theories range from hundreds of men dragging the stones to innovative techniques like using expanding wet wooden wedges for precision carving.

Machu Picchu, 101

Machu Picchu was built right on top of two intersecting fault lines, which makes it even more baffling how its temples and terraces have survived for more than 500 years—especially since no mortar was used to hold the precisely cut stones together. As this three-minute NatGeo video explains, this ingenious construction method allows the stones to bounce in place when earthquakes hit, shaking and rattling but rarely collapsing.

Inca trail interactive map

Machu Picchu gets all the attention, but it’s definitely not the only Inca ruin in the area. Some dedicated trekkers opt to see the sites through a multi-day hike down the Inca Trail, which spans 26 miles from the Sacred Valley to Machu Picchu and reaches elevations as high as 13,800 feet above sea level. This 3D tour gives a sneak-preview of the ruins along the route, and the intense topography.

A virtual reality experience of Machu Picchu

If you can’t make it to the Andes, this virtual-reality experience—created using 360-degree cameras, and 3D modeling and sound design—is the next best thing. It lets you explore all the site’s major landmarks, including the Sun Temple and the Temple of the Condor, while listening to the sound of the wind whipping through the ruins, birdsong, and audio commentaries from expert guides.

Watch the annual three-day revamp of the Q'eswachaka bridge

Rebuilt every year since the Inca empire, this bridge still is used today by locals who want to traverse the 120-foot-wide gorge that runs beneath it. This three-minute video shows just how much effort goes into its restoration.

Human sacrifice in the Inca Empire

In the lands ruled by the Incas, mountain deities were well-respected and related summits were often selected as places for making the most important of all offerings — human sacrifices.

Yale returns Inca artifacts to Peru

From the time he came upon Machu Picchu in 1911, Hiram Bingham began removing artifacts and human remains from the site and bringing them back to Yale University. Yale's Peabody Museum held them for 100 years, despite demands by the Peruvian government and the public that they be repatriated. Finally, in 2011, Yale returned thousands of items, including ceramics, jewelry and human skeletons.

See a 3D reconstruction of Tenochtitlan, the Aztec capital that was home to an estimated population of 200,000 to 400,000.

Explore the Mayan temple at Copan

Copan is a Mayan temple located in western Honduras, where Mayans dwelled for roughly 2,000 years. The acropolis there was abandoned in the tenth century but rediscovered in the 19th, and excavations of its many structures and tunnels continue to reveal more about Mayan history. Click through to tour its major temple and tunnels in this informative, impressive interactive.

See the major Egyptian monuments in high definition

The massive, hard-to-imagine mammoth structures can be viewed here in 4K, dramatic detail with this stunning video. Visit the Great Pyramids of Giza, the temples at Karnak and Luxor, the Valley of the Kings, and more millennia-old monuments.

A Native American city in present-day Illinois once rivaled the size of medieval London

Around 1100, the city of Cahokia, the largest Mississippian settlement, reached a population of 15,000 to 20,000. Located across the Mississippi River from present-day St. Louis, it featured massive earthen pyramids and a central plaza the size of 35 football fields.

The high-tech mechanisms of the Roman Colosseum

The Roman Colosseum is one of the most iconic amphitheaters in the world and still partially stands today. Aside from its sheer size, the arena was equipped with some of the most high-tech engineering from the classical world, including sophisticated lifts, a huge retractable awning, and an underground network of tunnels, elevators, and trapdoors.

What Stonehenge sounded like

Researchers built the first scale model of the world's best-known prehistoric stone circle, Stonehenge, to study its acoustic properties. Built approximately 5,000 years ago, the landmark in southern England has puzzled historians for centuries, but...

What we know about the mysterious colossal squid

The colossal squid, the world's largest invertebrate, remained hidden from human discovery until nearly a century ago. Explore the world of the enormous and mysterious creature, including its features, habitat, and scientific significance. You can even plan a visit to the Museum of New Zealand Te Papa Tongarewa and marvel at a real-life display.

What were the Aztecs really like?

Does the society live up to its blood-thirsty stereotype? Archaeologist Eduardo Matos Moctezuma answers this question and more in this short article. Moctezuma was the principal excavator of the major Aztec archaeological site Templo Mayor in the 1970s. He shares how the culture grew from a combined emphasis on war and agriculture, and ruled one of the world's largest cities at the time.

A look at some of the world's most unique churches

From a skeleton-adorned church in the Czech Republic to wooden churches built without nails in Russia, this video explores some of Christianity's most intriguing architectural feats. These places of worship were built in remote areas throughout history, and show amazing innovation. See a fascinating glimpse into the overlooked structures, along with stories of how and why they came to be.

A town in Peru holds a massive fistfight on Christmas

In Santo Tomás, Peru, Christmas Day features Takanakuy—organized public brawls where residents settle disputes through ritualized fistfights. The tradition, rooted in Andean customs, acts as a communal reset before the new year.

The spiralling structure of the Guggenheim Museum in New York is itself a work of art

The Solomon R. Guggenheim Museum is a UNESCO World Heritage Site in Manhattan's Upper East Side. The contemporary art museum, known for its unique spiral structure, was Frank Lloyd Wright’s final work.

20 of the world's most iconic big rock wall climbs

Big wall climbs are tall rock faces that require climbers to "pitch" multiple times during the ascent—that is, reuse a rope. They also often portaledge, or sleep, at least once during the climb. Topping the list is California's El Capitan.

Take a virtual tour of the International Space Station

The ISS is the largest human-made object in space. Its modules were meticulously connected by robotic arms and astronauts during slow, careful spacewalks, creating a structure with over eight miles of electrical wire.

An acropolis is a fortified hill, a common center point of Greek city-states

The Acropolis of Athens is the most famous of the Greek structures, the site of the iconic Parthenon standing tall over the city. It has stood for thousands of years and undergone myriad transformations through war and shifts in politics and culture.

The containment apparatus at Chernobyl is the world's largest movable metal structure

Completed in 2016, the "New Safe Confinement" is a €1.5B megastructure—the largest movable structure ever built. It was assembled next to the damaged reactor, then rolled into place along a special track to seal the site for at least 100 years.

Lidar's discoveries: 32 forts revealed by the laser tech

Lidar is a cutting-edge tool using lasers from an aircraft to map the elevations of huge swaths of land across the world. This technology has been especially effective in archaeology. It has revealed dozens of lost major historical sites concealed beneath overgrown brush and forests. From Canadian forts to Mayan settlements, check out these 32 significant finds from lidar.

The Smithsonian is the world's largest museum complex

With 21 museums and the National Zoo, the Smithsonian Institution is the world's largest museum complex. Eleven of those museums sit directly on the National Mall, and all offer free admission to the public.

Meet the Marree Man, one of the world's largest works of art

In the summer of 1998, a pilot flying over the Australian outback discovered a geoglyph 1.7 miles long featuring an aboriginal man hunting. The massive work of art is one of the world's largest.

Explore the archaeological treasures of Pompeii, the city buried under volcanic ash when Mount Vesuvius erupted in 79 CE.

In 1963, a basement renovation in Turkey revealed a passageway to a hidden, multilevel underground city that once housed as many as 20,000 people

Take a 3D tour of the Hajj, Islam's annual pilgrimage to Mecca, undertaken by over 1.5 million Muslims.

Massive 3D printers have been used to build homes by stacking layers of 'concrete toothpaste,' a fire-resistant material that effectively insulates against outside noise.

See photos of Meteora, a mountainous site in central Greece, home to 14th-century monasteries perched atop soaring outcroppings.

For centuries, Niagara Falls has been a magnet for daredevils seeking to conquer one of nature's most powerful wonders, with its 200-foot drop and water rushing at 32 feet per second with 280 tons of force.

Legendary architect Frank Lloyd Wright designed the SC Johnson headquarters in Wisconsin, aiming to make a cathedral-like workplace

Explore our favorite visualization of the immense scale of space, from an astronaut to the size of the observable universe

NBA superstar Victor Wembanyama spent the 2025 summer training with monks in central China to enhance his body and mind.

The syncytiotrophoblast is the outer layer of the placenta and the largest human cell, spanning an area about twice that of a king-sized bedsheet.

Explore fun facts from the USPS, including unique post office buildings, a stamp that traveled past Pluto, and more.

When you complete a CAPTCHA on a website to prove you are human, you may be unknowingly training algorithms for self-driving cars, whose systems require training data to help identify crosswalks, bicycles, and other outdoor objects.

In 2025, four executives from large tech companies were given positions in the US Army Reserves—including Palantir Chief Technology Officer Shyam Sankar, which reinforced Palantir's ties with the US military and its role as a leading defense partner.

'Grand Canyon of the Yellowstone,' a work by American painter Thomas Moran, inspired Congress to establish Yellowstone National Park.

See these 16 pieces of art evoking phobias of snakes, flying, spiders, and more. 

Against his wishes, Albert Einstein's brain was removed before his cremation, and the pathologist responsible stored it for decades in mason jars within a beer cooler.

The US Constitution is widely regarded as the longest-standing written national constitution still in force—see how it has influenced rights worldwide.

A 2019 Facebook event called on attendees to "Storm Area 51, They Can't Stop All of Us," resulting in countless memes, the creation of a music festival, and eventually the arrests of those who did try to approach the area.

See how Budweiser's famous Clydesdales spend their days at Warm Springs Ranch, where roughly 70 to 80 of the beer brand's giant horses can be found at any given time.

Iran's Revolutionary Guard Corps is independent of Iran's regular army and is one of the most powerful and influential military-political organizations in the Middle East.

The first horror movie is believed to be George Méliès' 1986 short 'The Haunted Castle,' which pioneered the use of special effects

The Nasdaq's 'Magnificent 7' companies are responsible for roughly 40% of the Nasdaq 100 index's gains, while the remaining 93 companies account for the other 60%.

Sunflowers have long been a symbol of nuclear disarmament because they can extract large amounts of radioactive cesium from soil.

US intelligence allegedly pursued more than 600 schemes to assassinate Cuban revolutionary Fidel Castro.