The three theories explaining how the pyramids were built

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.

Stonehenge, explained

Located about 90 miles west of London, Stonehenge was built around the same time as Egypt’s Great Pyramid. Its 30-ton stones have fascinated archaeologists and historians for centuries, making it one of the world’s most studied prehistoric sites.

Scholars argue Egypt's Great Sphinx depicts the pharaoh Khufu

Egypt's ancient marvel, the 66-foot, 4,500-year-old Great Sphinx, is believed to stand as a guard to the great Giza pyramids—or tombs—of pharaohs Khafre and Khufu. Archaeologists have long debated which of the two leaders' faces is on the great monument, the father (Khufu) or the son (Khafre).

The Maya built their cities with advanced engineering

Maya cities featured pyramids, palaces, causeways, ball courts, and water-management systems that were engineered to support large populations—often tens of thousands—without the use of metal tools, draft animals, or wheeled transport.

Aliens have invaded ancient history

Avid fans of archaeology can sometimes fall prey to unsubstantiated claims like "aliens built the pyramids," provocative, dubious theories which fall under the category of pseudo-archaeology. Many of these claims are premised on hidden biases toward non-Western cultural heritages. This professor explores the hidden contours of pseudo-archaeology in this 12-minute TED talk.

Explore the major archaeological sites of Egypt's 3,000-year history

With this interactive map, you can see when and where every major monument was built, from the Great Pyramid in the Nile River delta to the Greek temple of Isis near contemporary Aswan.

Why only one of the seven wonders of the ancient world still exists

Greek writers recorded lists of great structures that were later codified by Renaissance writers. The definitive list includes the Colossus of Rhodes, the Giza Pyramid (the only existing one today), the Hanging Gardens of Babylon, the Temple of Artemis at Ephesus, the Statue of Zeus at Olympia, the Mausoleum at Halicarnassus, and the Lighthouse of Alexandria.

What it's like to go inside the Great Pyramid of Giza

Tourists can actually enter the ancient wonder, taking a 15-minute jaunt through tight spaces some describe as uncomfortable. The focal point of the journey is the chamber of the dead pharaoh, historically significant but not always visually compelling. The author describes it as a cool bucket list item but wouldn't repeat it.

Why are ancient ruins underground?

When cities fall into disrepair, it's often easier to flatten what you can and build on top. This is why modern archaeologists frequently discover ruins underground, revealing generational layers of cities rebuilt over time. This video explores major examples of this principle, from ancient Troy to even modern Seattle.

Why water towers are built that way

Earth's total mass is equivalent to 13 quadrillion Egyptian pyramids of Khafre

Newton's law of universal gravitation was used to calculate the value after Henry Cavendish torsion balance experiments determined the missing value of the universal gravitational constant from Newton's equation.

Go inside the Washington Monument

This video tour of the Washington Monument explores its interior, construction delays, political battles, memorial stones, earthquake damage, and later modernization—showing how symbolism, engineering, and 19th-century politics shaped the nation's tallest monument.

The Greeks weightlifted using massive stones—but viewed muscles differently

Ancient Greek art is replete with humans with muscular physiques, but there is very little evidence they knew much about proper weightlifting. There are just a few stones with inscriptions hinting at their weightlifting use. This article exposes some of our modern assumptions about muscle development, suggesting the Greeks thought differently about strength than we do today.

Greek-Egyptian scientist Heron invented automatic doors for a temple

The doors opened when a fire was lit in front of the temple, causing heat and pressure to build in a nearby vessel that would force its contents into a higher secondary vessel. This secondary vessel would lower, pulling the doors open. When the fire extinguished, the pressure and liquid in the vessel would reverse course, closing the temple doors.

Pyramid or plate? Why nutrition guidelines change

Those who remember growing up with the age-old food pyramid may be resistant to dietary guidelines changing, but experts agree that the food pyramid recommendations held serious flaws. It suggested, for instance, that meat and junk food were meant...

Before dynamite was invented, Erie Canal builders blasted rock with gunpowder

Constructed decades before the invention of dynamite, the Erie Canal’s toughest obstacles were blasted through using black powder charges.

Roman concrete lasts longer than modern recipes—and even gets stronger

Today's concrete is made by binding ingredients, including chalk and silica sand, at high temperatures. Unfortunately, it weakens when exposed to salt water. This article explores how and why scientists are studying ancient Roman concrete, which grows stronger when exposed to salt water.

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

Da Vinci’s ingenious self-supporting bridge

Without using glue or nails, the brilliant polymath Leonardo Da Vinci was able to construct a sturdy bridge of wood logs. This video unpacks the genius civil engineering behind this concept and offers a visual demonstration of how it worked. See how Da Vinci accomplished this feat without using permanent parts, and how his bridge got even stronger as weight and force was added.

How the underground maze below the Gaza Strip works

Hamas militants have constructed a web underneath the Gaza Strip filled with tunnels, residential areas, bunkers, and more. This article and illustrations explore the underground maze as detailed in photo and video evidence and witness accounts.

Ancient Egyptians developed the first pregnancy test—and scientists tested it in the 1960s

A papyrus from about 1350 B.C.E. discusses a test in which a woman would urinate on wheat and barley seeds over the course of several days. If the barley grows, she's having a male child; if the wheat grows, it's a female child; and if nothing grows, she's not pregnant. Scientists went on to test this theory in 1963 and found that about 70% of the time, the urine of pregnant women did promote growth whereas the urine of nonpregnant women didn't—perhaps due to estrogen levels in the urine.

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.

Each design detail on the US $1 bill has significance

The eye in the triangle floating above the pyramid, for instance, is “the Eye of Providence watching over and ensuring the endurance of the structure of the American government.” This article details every design choice’s significance on the dollar—and a few conspiracies around these choices as well.

How NASA plans to build a lunar base, from roads to habitats

The Apollo program aspires to return humans to the moon—and to build humanity's first permanent habitat on its surface. The project involves complex construction plans, including creating roads from moon dust, baking bricks to build habitats, and more.

Most Mardi Gras floats are constructed from foam and papier-mache

The moving sets were originally drawn by mules and made of wood. Now, they're motorized and intricately crafted from foam and papier-mache. This virtual tour of Mardi Gras World—a New Orleans warehouse responsible for floats for various krewes, as well as for Disney and Six Flags—showcases their vibrant designs.

The Triple Crown, explained

Only 13 horses have ever won the Triple Crown—one of the most elusive titles in American sports. This explainer breaks down how the series works, why it's so difficult to win, and the legendary horses that defied the odds across the Kentucky Derby, Preakness Stakes, and Belmont Stakes.

Breaking down the details on how the art heist at the Louvre unfolded

On October 19, 2025, several people dressed as construction workers climbed a construction lift and broke into the Louvre, stealing roughly $100M of crown jewels. This podcast breaks down the specifics of the heist.

Stanford built a Google Maps for the Roman Empire, revealing how much it cost to travel in the ancient world

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.

See how fireworks are made and learn how metals like magnesium and copper are responsible for different colors.

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

The Mona Lisa's celebrity status and repeated restorations have obscured what made the painting so revolutionary for its time

Before the current East Wing ballroom project, only two White House renovations in the past 100 years cost more than $10M.

Watch how algorithms can be designed to train themselves and self-improve without human input, to the point where the optimized code is too complex for programmers to understand.

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

Many legends about George Washington, including his supposed wooden teeth and the story of cutting down the cherry tree, lack evidence.

Recent research found that the brain doesn't seem to massively rewire following amputation—upending earlier beliefs about the cause of phantom limb pain.

According to the physics of black holes, our 4D reality may be a hologram—a projection of information coded on a 2D surface on the edge of the universe.

Trace how the Bill of Rights, inspired by centuries of political theory, took shape between 1774 and 1789.

For centuries, it was common to sleep in two shifts: a few hours at the beginning of the night, and a longer period beginning around midnight

While the sun's gravity keeps the planets in orbit, their gravity also pulls on the sun, causing it and everything else in the solar system to orbit around a mutual balance point called the barycenter—the true center of the solar system.

Watch this video that uses Lego bricks to explain how venture capital works.

Corals are themselves not coral reefs—the term refers to the tiny marine invertebrates that build the rigid reef.

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.

Discover the catastrophic consequences of a failure of the US electrical grid—something that is more likely than many Americans think.

The boiling temperature of water decreases with increasing elevation because the molecules need less energy to overcome the lower atmospheric pressure associated with thinner air.

Gerrymandering works through two techniques: cracking opposing voters across districts to dilute their power, and packing them into a few to waste their votes in lopsided majorities.

Scientists have struggled to pin down Ebola's natural reservoir species for decades, but the available evidence suggests that it's very likely fruit and insect-eating bats found in Africa.

The first robot in literature may have been a 'mechanical man' in 1907's 'Ozma of Oz,' a book in L Frank Baum's 'Wizard of Oz' series.

A Yale student wrote a profound essay about the consulting industry's influence on elite college students that was published in a book of her writing after she died in a post-graduation car accident.