The Aztecs synced their solar calendar with a complex 260-day ritual cycle

The Aztecs worshipped a vast pantheon of more than 200 gods.

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.

See the path Spanish conquistadors took to conquer the Aztecs

Spanish expeditions reached central Mexico as the Aztec Empire was expanding its influence. After securing bases in the Caribbean, they advanced west into Aztec territory, triggering a cascading conflict depicted in this interactive map and timeline.

Human sacrifice reinforced Aztec political control and religious belief

The Aztecs controlled a vast territory through military might and intimidation. One very key tactic of control was the ritual of human sacrifice. While an effective scare tactic, the ritual was also grounded in deeply held beliefs that the world was sustained by blood.

The Aztec Empire ruled over 80,000 square miles of central Mexico for nearly a century—until a small band of Spanish conquistadors brought it down in 1521.

Aztec mythology informs the Day of the Dead

The ancient people believed the dead journeyed to Mictlán, the Land of the Dead. To get there, they had to travel for four years through nine underworld levels, with the final being occupied by Mictlantecuhtli, the Aztec god of death, and his wife Mictecacíhuatl.

The Aztecs worshipped Mictecacihuatl, goddess of the underworld

Some elements from ancient festivals honoring Mictecacihuatl and other deities, like incense, skeleton imagery and marigolds, have been incorporated into modern Day of the Dead celebrations, possibly indicating that the holiday blends indigenous and Catholic traditions.

Using AI to rewrite and revive Aztec tales

Despite being vanquished by the conquering Spaniards in the 16th century, the Aztecs' culture endured through their descendants and rituals, as well as texts that escaped destruction at the hands of the Europeans. These texts, known as codices and preserved in part by Christian monks, revealed intimate details of life as an Aztec in the Middle Ages. Today, AI programs allow students to learn the Aztec's language, Nahuatl, further preserving their heritage.

Watch a traditional Aztec fire-serpent dance rooted in Mexica mythology

This video captures a performance of a Xicauhuatl—or fire-serpent—dance, rooted in Mexica beliefs that these serpents carried the sun across the sky. The performance highlights the fire serpent’s central role in Aztec ritual and storytelling.

The ancient Roman origins of the leap year

The earth's orbit around the sun takes about 365.2422 days, leaving farmer almanacs the awful job of pretending the calendar year fits into a whole number. This article explores the modern origins of the civil solar calendar and its leap year. The Julian calendar, named after the Roman emperor Julius Caesar, cut the calendar year into 365.25 days, gifting the public an extra day every four years. Learn more of the history here.

Teotihuacán was already ancient when the Aztecs encountered it

By the time the Mexica reached Teotihuacán, the vast city had been abandoned for centuries. First settled around 400 BCE, the inhabitants developed monumental temples, canals, and a carefully planned urban grid centered on the Avenue of the Dead.

The Aztec Empire began as a three-city military alliance

The Aztec Empire emerged in 1428 when Tenochtitlan, Texcoco, and Tlacopan formed the Triple Alliance, combining military power and tribute networks. This pact transformed the three city-states into a dominant regional empire that rapidly expanded across central Mexico.

The Aztec capital of Tenochtitlan fell after a brutal 75-day siege.

By identifying patterns in the periodic movements of the sun, moon, and Earth, ancient civilizations realized that identical eclipses repeat about once every 6,585 days, known as the saros cycle.

See how the elite warriors of the Aztec Empire trained

This video explores the Aztec military’s elite Eagle and Jaguar warriors, known for their courage and combat skills, and highlights their rigorous training regimen. It concludes with a workout routine modeled on their methods.

See a day in the life of an Aztec midwife

This illustrated story follows Xoquauhtli, a midwife in the Aztec Empire, as she juggles childbirth duties during the festival of Teteoinnan, navigating the tension between professional responsibility and participation in the empire’s religious ceremonies, including ritual sacrifice.

New Year's Eve celebrations date back to ancient Babylon

Rather than celebrating in winter, the Babylonians honored the vernal equinox, a day in late March with equal amounts of darkness and light that signaled the start of a new year. They celebrated with Akitu, an 11-day festival.

Learn how the Egyptians, Romans, and other ancient civilizations worshipped the sun

In Egypt, the pharaoh was seen as the living embodiment of the son of Ra, the sun god. In Mesopotamia, the sun god Shamash was a divine judge whose light could reveal the truth. Huitzilopochtli, the Aztec god of sun and war, was thought to require sacrifices to prevent the universe's destruction.

How the months of the year got named

Curious about how the months got their names? This article from The Old Farmer's Almanac explores the origins of today’s Gregorian calendar. Based on the ancient Roman lunar calendar, the months were named after Roman gods until winter when the names changed to numerical titles. Read along to learn the significance and intentions behind labeling each lunar cycle.

Learn to speak the ancient Aztec language Nahuatl

Across the Aztec Empire, you'd be met with variants of Nahuatl, the indigenous language still spoken by approximately 1.5 million people today. This free, self-paced online university course teaches the Veracruz variant, beginning from the language's "piltlahcuiloltzitzin"—or alphabet—to how to conduct specific "tlamachtiliztli" or ceremonies.

A bird's eye view of Teotihuacan

Dubbed Teotihuacán or City of the Gods by the Mexica, this city was first inhabited in the 2nd century CE and ultimately became an important cultural landmark for the Aztec empire. Located roughly 30 miles north of Mexico City, contemporary ruins contain a 200-foot tall Pyramid of the Sun, ancient neighborhood grids, and more. Explore the city in this virtual helicopter tour.

An Aztec skull whistle discovered in the 1990s was mistaken for a toy

In the late 1990s, archaeologists unearthed a sacrificed man clutching two skull-shaped clay whistles at a Mexico City temple to the wind god Ehecatl (eh-HEH-kahtl). Initially dismissed as toys, the instruments produce a scream-like sound that modern brain scans show triggers fear and urgency responses in listeners. This podcast explores the discovery.

Early timekeeping tools included sundials, water clocks, and astrolabes

Astrolabes also provided a person's latitude based on the height of the stars in the sky, thus aiding in navigation. Incense and candle clocks relied on the constant burning rate of fire to track the passage of time based on premarked locations with equal-interval spacing.

The hour originated from an ancient Egyptian astronomical system

The movements of astronomical objects, measured in a day and a year, form the foundation of our sense of time. The Egyptians divided each day and night into 12 time eras, using arbitrarily selected stars as references rather than movements of specific celestial objects.

What was the longest year in history?

In 46 BCE, Julius Caesar declared the year would last 445 days. This four-minute podcast and accompanying article explain why. Caesar wanted to make the following year start after the winter solstice, an achievement attainable due to his tinkering with the Roman calendar. But to start the year right, Caesar had to stretch the transitional year, leading to the creation of Caesar's Year of Confusion, the longest year in history.

The Maya were an ancient Mesoamerican civilization that built dozens of major cities across present-day Mexico and Central America.

See a 3D reconstruction of Tenochtitlan, the Aztec capital

From the Greek for 'star taker,' the astrolabe allowed individuals to tell time and determine their latitude based on the position of the sun or other stars, as well as calculate the height of objects.

Play a game inspired by Aztec and Mayan mythology

This free online game, Descent of the Serpent, guides players through Mesoamerican myths as they challenge the god Tezcatlipoca. Along the way, it introduces monuments and artifacts with short explanations of their meaning in Aztec and Mayan cultures.

New research challenges the myth that Montezuma peacefully surrendered to Spain

For centuries, historians claimed Montezuma II willingly ceded control to the conquistadors, and that later Aztec resistance was a rogue uprising. Evidence now shows no peaceful handover occurred, revealing a far more turbulent and contested encounter between the two warring empires.

The iconic Aztec 'crystal skulls' were 19th-century fakes

The crystal skulls long displayed as Aztec artifacts were actually fabricated in the late 1800s, all linked to French antiquities dealer Eugène Boban. Anthropologist Jane Walsh's investigation exposed their modern origins, overturning a century of mistaken museum lore.

Asia's agriculture-focused set of 24 'small seasons'

In contrast to the four broad seasons and their basis in astronomy and climate, ancient farmers in China and Japan had many more and varied seasons (or "sekki). Take Keichitsu (March 6 to 21), for example: this means "going-out of the worms" when bugs come out from hibernation.

The world's different calendars, explained

The calendar we use to mark the days, months, and year can feel set in stone, but the history of calendars shows these organization systems can and do change. Parse the fascinating, complex details of the Gregorian, Julian, Chinese, Hebrew, and many more calendars in this comprehensive, well-executed explainer video.

The Maya believed every person is born with a spirit companion

In Maya belief, each person is linked to a spirit or animal companion associated with one of the 20 sacred calendar day signs. Enter your birthday and discover your companion, which is believed to reflect your personality traits.

Make these Aztec-inspired amaranth and honey skulls for Dia de los Muertos

On the Day of the Dead, ghosts enjoy earthly delights amid Mexican cemeteries. Baskets of sweet breads and tamales grace graves, while altars honoring the departed display hot chocolate and chicken legs. Hear from experts why this morbid day emphasizes the significance of offering foods loved by the dead. Intrigued? You can learn to make them yourself with recipes provided.

The Ancient Chinese harnessed solar power for heating and cooling 6,000 years ago

Neolithic Chinese homes faced south for winter sun warmth, while overhangs shielded them from high summer sun. These efforts also influenced urban planning, with cities aligning streets east-west for optimal solar exposure.

The chemistry of ancient tacos

This 16-minute podcast explores the chemistry of Mesoamerica's corn tortillas, which involve a 3,500-year-old chemical process called nixtamalization that releases vitamins, including niacin, one of the essential B vitamins. This process also makes the tortillas softer and more delicious. Corn tortillas were a staple in Mesoamerica, and the archaeologist interviewed in this podcast argues cultures like the Aztecs and Maya wouldn't have thrived without nixtamalization.

The evolution of Mexico City, from the Aztecs to today

The sprawling modern city situated in the Valley of Mexico began a millennium ago as an island in the middle of Lake Texcoco, connected to land through a series of causeways. Learn how the Aztecs built Tenochtitlan, how the Spaniards conquered it, why the lake disappeared, and more with this visually rich history and geography of a city of 9 million people.

The winter solstice has been celebrated globally for millennia

From gatherings at Stonehenge in the UK to celebrations of the triumph of Mithra in Iran, cultures around the world have marked the shortest day of the year in a variety of ways for a very long time. Here are eight known to us today that endure.

Researchers once thought Stonehenge functioned as a precise astronomical computer

In the 1960s, scientists used early computers to analyze the stone layout at Stonehenge, arguing it could predict eclipses and other celestial events. This BBC Sky at Night Magazine piece explains how the theory arose—and why scholars now doubt it.

The solstice has been celebrated globally for millennia.

COVID-19 disruptions revived ancient chinampa farming in Mexico City

When the pandemic disrupted food supply chains, chinamperos—farmers who cultivate the Aztec-era “floating gardens” built atop shallow lakebeds—shifted to direct sales in the city, boosting their visibility and reconnecting residents with a longstanding local agricultural tradition.

How lunisolar calendars work

Despite being called Lunar New Year, the Chinese calendar that the holiday is based on is actually lunisolar, or based on both the sun and the moon. Many religious holidays—including Easter, Ramadan, Chinese New Year, and Passover—do not have fixed dates according to the now-ubiquitous Gregorian calendar.

The holiday has evolved alongside its participants' cultural identities

The Day of the Dead blends various traditions, including Aztec myth, Mexican heritage and Chicano identity. That makes for a complex and evolving holiday. This conversation between Cynthia Vidaurri, a Smithsonian folklorist, and Lalo Alcaraz, a cultural consultant for “Coco,” analyzes how the varied influences have created the modern holiday.

How the ancients calculated Earth's size correctly

Watch this seven-minute video to hear Carl Sagan explain how ancient Greek polymath Eratosthenes correctly calculated the size of the Earth in the third century BCE. At some point, Eratosthenes noticed a discrepancy in the length of shadows cast in different cities during the summer solstice. This observation grew into a simple experiment that enabled Eratosthenes, the head librarian at the Library of Alexandria, to calculate the Earth's size precisely.

How people imagine a calendar year

It turns out everybody imagines the abstract calendar year in a simple, concrete way, though there are surprising differences between the exact model and shape of each image. Dive into one writer's collection of tens of thousands of questionnaire responses showing the fascinating consistency and divergence of how people visualize time.

Saturnalia was a Roman festival that helped shape Christmas

Ancient Romans celebrated Saturnalia in mid-December, honoring Saturn, the god of agriculture, with week-long street festivals. These celebrations featured gift exchanges, lavish meals, and gambling, which was prohibited in public at the time.

Tenochtitlan, the Aztec Venice of Mesoamerica

Tenochtitlan was the capital city of the Aztecs, founded around 1325 on an island in Lake Texcoco, in what is today Mexico. It was a major political, economic, and religious center until its destruction by the Spanish in 1521. This video explores the marvels of the city, which began as an island but grew via causeways and in-filled land and culminating in a North American Venice.

China has used several different calendars because of changes in government structure

For many centuries, during which China was an imperial nation, the lunar/lunisolar calendar (aka the “rural calendar”) was the basis for organizing the year. Several attempts were made over the decades to switch to the Gregorian calendar—which begins Jan. 1—but it wasn’t until the People’s Republic of China was founded in 1949 that it stuck.

How the brain processes a calendar year

When most of us picture a calendar year, we have a foggy image in our minds of the months, in rough, calendar-like grids. But for some folks, that picture is a whole lot more clear. Around 1 percent of the population has a strange ability known as "calendar synaesthesia," which means they're able to visualize in crisp detail an elaborate calendar of the months of the year. Learn how it works here.