During the Medieval Period, urban populations grew significantly

Paris and Boston were redesigned partly to combat cholera's spread

Georges-Eugène "Baron" Haussmann, who oversaw Paris's redesign in the 1800s, replaced many of the city's narrow streets with wide boulevards. This was done at least in part to bring more air and light into the city to help control cholera. Architect Arthur Gilman redeveloped Boston's Back Bay to similarly combat cholera, among other reasons.

Medieval Europe was a patchwork of hundreds of competing states

In the Middle Ages, Europe was divided into hundreds of kingdoms, duchies, and territories, bearing little resemblance to modern borders. This map captures the political landscape in 1444, as the Ottoman Empire was in the midst of its rise.

Money—not land—became Europe’s key economic driver in the Middle Age

During the medieval commercial revolution, money gradually replaced land as the primary economic commodity. Expanding trade, markets, and finance transformed Europe’s economy—laying foundations, historians argue, that were essential for the later Industrial Revolution.

The Greek city of Alexandria in Egypt helped form the template for modern cities

It was designed by Dinocrates, who studied under Hippodamus, the father of urban planning. Hippodamus preached that urban planning should take into account function, culture, and politics. Dinocrates' design of Alexandria meant applying Hippodamus' teachings on a scale never before attempted.

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.

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.

Jakarta surpassed Tokyo as the world's largest city in 2025

Asia is the epicenter of global urban population, hosting most of the world's ten largest cities by population. The top three are Jakarta, Indonesia, Dhaka, Bangladesh, and Tokyo, Japan.

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.

Rise and fall of the Byzantine Empire in 60 seconds

In 330 CE, Emperor Constantine made the bold move of shifting the Roman capital to Byzantium and renaming it Constantinople. This decision helped shape the Eastern Roman Empire, or what we now call the Byzantine Empire. Here’s how the city rose to global prominence, and why its legacy lingers today.

A map of Barcelona from 150 BCE to 2010

Watch Barcelona evolve from Iberian settlements in 150 BCE to Spain’s second-largest city in the modern day by toggling this chronological series of 27 maps. Accompanied by a short contextual blurb, each map shows Barcelona’s steady urbanization over more than two millennia. For those captivated by the interactive, read this interview with one of the project’s key cartographers. He discusses how the mega-map was created and what it reveals about Barcelona’s history.

Watch the history of human migration that led to civilizations

Starting in Africa where they hunted with spears and fires, humans would gradually move out of the continent over thousands of years as they navigated crossing deserts, rivers, uneven terrain, and shifting climates. Development of technology, language, farming, and other societal structures helped build up the first civilizations.

Charlemagne sparked a medieval revival of learning and Roman culture

During the Carolingian Renaissance, Charlemagne—the king of the Franks and later the emperor of much of Western Europe—and his successors promoted education, the arts, and scholarship. Monasteries preserved hundreds of Roman texts, while architecture and artistic styles drew inspiration from classical Rome.

Maritime trade in the Mediterranean accelerated during the late Bronze Age

This map illustrates the vibrant trade networks of the eastern Mediterranean during the Late Bronze Age (circa 1500–1200 BCE), highlighting an era of growing interconnectivity among major powers including Egypt, the Hittite Empire, Mesopotamia, and others.

Cities bore the brunt of the migrant surge in the 2020s

During the 2022-24 migration surge, cities such as New York, Chicago, and Denver faced shelter overcrowding, strained public services, and housing shortages—while the upfront costs fell almost entirely to states and cities.

The Erie Canal transformed New York City into America’s banking capital

By redirecting western trade through New York Harbor, the canal turned New York into the nation’s commercial hub. This surge in commerce shifted financial power from Philadelphia to Wall Street, establishing the city as America’s banking capital.

Florence as it was: a digital reconstruction of a medieval city

Florence, Italy, is widely considered the birthplace of the Renaissance in Europe, where artists, poets, architects, and entrepreneurs renewed interest in ancient cultural forms. Using data from primary works, researchers have created a digital reconstruction of the city where users can explore buildings, artworks, and more.

The Aztec Empire explained

Tenochtitlán grew into a powerful city-state supported by innovations such as chinampa farming and its central role in the Triple Alliance. Spanish forces later exploited internal rifts to overthrow the empire, but the city’s legacy endures in modern Mexico City’s historic core.

How parking infrastructure reveals a region's values

As cars became more popular, the need for city parking increased. In Europe, well-established cities with limited space generally opted for more expensive underground parking beneath public spaces to preserve aesthetics. Available land and decentralized planning in the US saw more parking lots and garages built. These decisions reveal broader policy realities for these regions.

The recorded history of crude oil use, starting with Babylonians waterproofing boats

The ancient civilization located in modern-day Iraq also used crude oil as mortar in construction, while the Egyptians used it to treat human remains during the mummification process. After the invention of the first motorcar in 1885 and the introduction of the affordable Model T in 1908, demand for crude oil skyrocketed.

How beer became a part of medieval culture

This history of beer's evolution during the Middle Ages unpacks how the brewing process, which killed harmful bacteria, made beer a safe alternative to water. That fact, along with the Catholic church condoning (and, in some cases, producing) the beverage, helped it evolve into a major commodity.

Volcanic activity may have triggered the Black Death by spewing gases that led to crop failures in Europe, thus forcing the import of grain ships with plague-infested fleas.

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 medieval meaning of your birthstone

Medieval people viewed birthstones very differently from modern jewelry marketing. Rather than simply being decorative, gems were believed to possess extraordinary magical, medical, and mystical powers. This article breaks down some fascinating insights into medieval gemstone beliefs, including that diamonds could fend off insanity and nightmares.

Volcanic activity may have triggered the Black Death by spewing gases that led to crop failures in Europe, thus forcing the import of grain ships with plague-infested fleas.

In medieval France, pigs were once put on trial

Pigs are omnivorous animals. There are hundreds of records of pigs killing and eating children in medieval Europe. In France, these tragedies often resulted in trials and then hangings. Some pigs were held in jail for years before being executed.

Until 1970, the Sorbonne was the most prestigious academic institution in France

Named after its founder, Robert de Sorbon, the former University of Paris was founded in 1253 to teach clerics and agents of royal and ecclesiastical institutions. The school was split into several autonomous universities after protests in May 1968.

Explore a map of Prince's Minneapolis

Prince might be the most famous and influential musician from a city brimming with them. This interactive map from Prince's estate lets you explore the city's locales that shaped him, from early residences to concert halls and recording studios.

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

Graffiti dates back to at least ancient Pompeii, where citizens scrawled messages to one another on public walls

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

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.

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.

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

Electrical grids worldwide must double their power delivery capacity by 2050 to meet surging demand from AI and electric vehicles.

Explore an interactive map of battles from the American Revolution, along with detailed summaries of each engagement

The power and influence of the American presidency have expanded significantly over time—far beyond what the founders envisioned.

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

The concept of phantom limbs, the perception that amputated limbs are still present, dates back to a French military surgeon in the 16th century.

The Russia-Ukraine conflict is the largest ground war in Europe since World War II in terms of casualties, forces mobilized, and displacement of civilians.

Hotels in Cannes, the glamorous city on the French Riviera, hire hawks to ward off seagulls during the city's famous film festival.

After NASA's Voyager 1 captured Earth as a single pixel as it left the solar system in 1990, astronomer Carl Sagan used the image to reflect on humanity's fragility and the responsibility to protect 'the only world we've ever known.'

Louisiana's 'Cancer Alley' is infamous for having some of the highest industrial pollution, toxic air emissions, and cancer risks in the US.

See 33 images that became central to huge scandals, including a young Charles and Camilla, Michael Jackson's baby on a hotel balcony, and Hugh Grant's mugshot.

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

Bone marrow (soft tissue found inside certain bones) generates roughly 500 billion new blood cells each day

Explore a list of the 100 best novels of all time, compiled by some of the world's best living writers, including Salman Rushdie, Stephen King, and Jennifer Egan.

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.

'Shogun,' a 1980s TV series, helped popularize sushi in the US by stimulating an American interest in Japanese culture.

Lesser-known phobias include turophobia, or the fear of cheese, and nomophobia, the fear of being without your cell phone.

Chaos theory—informally known as the butterfly effect—is the reason why weather forecasts are presented with probabilities rather than certainties.