The aqueducts and cisterns of Constantinople

The impressive walls of Constantinople

This video explores the land walls of Constantinople, built on the orders of Theodosius II in the mid-fifth century. They consisted of a triple line of defenses, studded with hundreds of towers and supplemented with a moat. The walls were besieged dozens of times, but were only broken in 1453 by the power of Ottoman cannons. As repaired by the Ottomans, the walls are still largely intact today.

The underground cities of the Byzantine Empire

This TED-Ed video explores the mysterious cave cities of Cappadocia. Although their oldest sections may go back to the Bronze Age, most of these subterranean complexes were excavated during the Byzantine period, when the locals went underground to take shelter from Arab raiders. Monasteries were also cut into pinnacles of the local tufa, and decorated with frescoes that have often survived to the present.

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

Eleven aqueducts funneled water to Rome's 1 million inhabitants

The Roman Empire's capital city was home to about one million people at its peak and managed to provide running water to many of its homes, fountains, and public baths. This was made possible by the 11 aesthetically grand aqueducts that poured into ancient Rome from the countryside.

Visualizing Byzantium in the year 1200

This is a computer reconstruction of the Byzantine capital at its apogee, just before the Fourth Crusade. Alongside detailed renderings of the Hippodrome and Hagia Sophia, it includes dozens of the imperial city’s less famous monuments, many of which can still be found in modern Istanbul. The reconstruction is a work in progress, and the Byzantium 1200 X account routinely posts updates.

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

The first coffeehouse opened in Constantinople

Coffeehouses began opening in modern-day Istanbul sometime in the 1500s. These cafes quickly became invaluable spaces for gathering and exchanging news and ideas.

The Alhambra’s medieval water system powered a palace-city

Built over centuries by Islamic rulers in medieval Spain, the Alhambra used canals and pressurized tanks to move water throughout the complex. Its sophisticated system supplied fountains, baths, and gardens, showcasing advanced medieval engineering.

The unusual connection between Venice and Byzantium

This article explores the complicated relationship between Venice and the Byzantine Empire. Venice grew up in the shadow of Byzantium, serving as a trade partner and faithful ally for centuries. Gradually, relations grew hostile, and Venetian ships would carry the Fourth Crusade to its fateful rendezvous with Constantinople. Visitors to San Marco can still see marble and porphyry from Constantinople, built into the walls of Venice’s preeminent church.

Exploring the Hippodrome of Constantinople

The Hippodrome had room for about 80,000 spectators (more than the Colosseum, but less than Rome’s Circus Maximus). It was simultaneously Constantinople’s premier entertainment venue and its greatest political theater: the emperor routinely watched the games, and sometimes communicated with the crowd through a herald. The worst riot in Byzantine history, the Nika Revolt, began when the factions of the Hippodrome united in opposition to Justinian.

The Chora Church, the height of Byzantine art

The Palaeologan Renaissance took place in the final centuries of Byzantium, and in the face of steep political and economic decline. Perhaps the movement’s most famous artistic product is the Chora Church in Istanbul. Renovated in the early fourteenth century by Theodore Metochites, a learned court official, the church features remarkably vibrant mosaics and frescoes. Although the building was recently reconverted into a mosque, most of its decorations are still visible.

The ancient Egyptians built prototypes of the modern Suez Canal

The idea to facilitate trade between the Mediterranean Sea and the Red Sea and connect the Eurasian continent was apparent even to pharaohs in the second millennium BCE. Though no physical traces remain, contemporary accounts attest to early, shorter versions of the canal, including from Herodotus.

Why water towers are built that way

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

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.

Water from four Great Lakes feeds Niagara Falls

Niagara Falls is powered by water from Lakes Superior, Michigan, Huron, and Erie. The Great Lakes basin spans over 260,000 square miles and holds nearly 20% of the world's surface freshwater—about two-thirds of which passes over the falls.

Learn how aquifers and wells provide the largest reserves of accessible freshwater on Earth

Roughly a third of Earth's freshwater is stored underground in aquifers—permeable and porous rock formations where water naturally flows from the Earth's surface and accumulates. About half of this groundwater is accessed through wells, a feat of engineering used for thousands of years.

Toronto's downtown has 18 miles of underground pedestrian tunnels

Known as the "Path," these tunnels have helped reduce pedestrian traffic on Toronto's busy downtown streets for over a century. They were first built by local business owners, prompting a network effect of add-on tunnels.

How Byzantine scholars supercharged Renaissance Italy

A brief survey of how Byzantine scholars changed the course of the Renaissance by introducing Classical Greek literature to Italy. These scholars and their students were responsible for translating, interpreting, and printing many of the most fundamental texts in the Western tradition. Without their efforts, the Italian Renaissance and Western thought would have been immeasurably poorer.

How the Code of Justinian formed the basis of modern law

This video explores the significance of Justinian’s Corpus Juris Civilis. The most important component of the Corpus, the Digest, collected the opinions of eminent Roman jurists. The Digest went on to become the legal framework of medieval Europe, and the basis for the civil codes used across two-thirds of the globe today—an underappreciated legacy of Byzantium.

The world’s largest waterfall is hidden underwater

The Denmark Strait cataract is an underwater waterfall in the ocean channel between Iceland and Greenland. It’s also the world’s largest waterfall. Standing 11,500 feet tall, the incredible natural landmark is more than three times the height of Angel Falls, the largest waterfall on land. Discover more about the features of this cataract, which, despite its massive size, is totally undetectable above water.

The 500 subsea cables that run the internet

Subsea cables carry the majority of data sent across the globe on the internet. An estimated 552 such cables—with more in development—lay on the ocean floor, their thickness similar to a garden hose, made up of optic fibers covered in copper.

Gladiators followed a mostly vegetarian, high-calcium diet

Analysis of skeletons from a gladiator cemetery at Ephesus by researchers at the Medical University of Vienna found little meat consumption but unusually high calcium levels—likely from drinking wood ash mixed with water to promote weight gain and protect vital organs.

A basement of mechanical systems—collectively called the technosphere—supports B2

Twenty-six underground air handlers heat, cool, filter and manage the humidity of the air across the biomes of Biosphere 2. The above-ground Energy Center complex provides continuous power to these and other systems, including heating and cooling water for laboratory experiments and personal use.

Watch a visualization of the construction of Chernobyl's sarcophagus

Built to contain the remains of Reactor 4 after the nuclear disaster, the "shelter structure" was constructed from about 400,000 cubic meters of concrete—enough to fill 160 Olympic-sized swimming pools. Construction required vehicles and cranes modified with special shielding to protect workers.

How landlocked Moscow became Europe's biggest city

It's far enough north to have avoided the nomadic hordes who, for centuries, raided the European plain to its south—but it's just south enough to still farm the land. What's more, Moscow is protected by the huge taiga forests and is guarded by rare east-west rivers in a continent with mostly north-south ones.

A database tracking water conflicts for thousands of years

This open-source database has logged more than 4,000 conflicts around water across 100 countries, cataloging water as a casualty, trigger, or weapon of the conflict.

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

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

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.

The history of many kitchen appliances involves unexpected discoveries and applications, including wartime radar turned hamster defroster and replacing an 'ice king' with heat-stealing boxes.

Most of the observable universe's volume consists of voids and supervoids—enormous regions of space with little to no galaxies, stars, or light.

Pure water does not conduct electricity because this flow of energy requires the movement of charged particles, and water is a neutral molecule.

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

Explore the history, structure, and species of Australia's Great Barrier Reef with this interactive journey narrated by Sir David Attenborough.

Poison ivy was sent to Europe in the 1600s as an exotic, ornamental oddity, where it was purposefully grown in the English royal gardens at Kew, the Faculty of Medicine in Paris, and a few other locations.

The term 'algorithm' originated from the Latinized name of al-Khwārizmī, a 9th-century mathematician whose works introduced Arabic numerals and the decimal-based numeral system to Europe and whose treatise 'Al-Jabr' gave algebra its name.

Crows are believed to have intelligence on par with a seven-year-old child and demonstrate complex behaviors, from problem-solving with tools to recognizing human faces.

Objects can be 3D printed with light by projecting 2D computerized tomography (CT) scans onto rotating cylinders of resin, which solidify upon exposure.

The Dracula character, now seen as the vampire archetype, was inspired by a seafood-induced nightmare its creator experienced.

The use of fungi to detoxify land and water—a process known as mycoremediation—has been used to clean up natural resources affected by the 2025 California wildfires.

Power lines are dotted with large, brightly colored balls to improve the visibility of these thin wires to helicopters and small planes and help prevent potential crashes.

SpongeBob exemplifies Aristotle's philosophy for living well because he understands that happiness doesn't come from external factors like money, recognition, or power.

The American Society of Civil Engineers' infrastructure report card gave the US a C in 2025, its highest grade since the project launched in 1998.

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

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

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.

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.

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