How the Ancients Shaped the Week

The seven-day week has endured for thousands of years, surviving empires, revolutions, religious shifts, and even a few determined attempts to replace it. Its origins lie in a mix of astronomy, astrology, religion, and ancient practicality — with a healthy dose of historical debate.

Many historians trace the roots of the seven-day week to ancient Mesopotamia, home to some of the world’s earliest astronomers. The Babylonians closely observed the sky and attached special importance to the number seven, partly because they recognized seven major celestial bodies moving independently: the sun, the moon, Mercury, Venus, Mars, Jupiter, and Saturn. Today, we know the sun and moon aren’t planets, but in the ancient world they were grouped together with the five planets visible to the naked eye. 

The Babylonians also used a lunar calendar, and the phases of the moon may have helped shape the structure of the week. A full lunar cycle lasts about 29.5 days, which can be divided into four roughly seven-day phases. Some scholars believe Mesopotamian societies, including the Sumerians and Babylonians, used these quarter-moon intervals as the basis for a recurring seven-day cycle, and this is one basis for our current week.

However, scholars continue to debate exactly how much the modern week is influenced by this Babylonian practice versus by ancient Jewish tradition. The biblical creation story helped cement the importance of the number seven in Jewish culture: According to Genesis, God created the world in six days and rested on the seventh. That seventh day became the Sabbath, a recurring day of rest and worship. Unlike many earlier calendars tied directly to lunar phases, the Jewish week evolved into a continuous repeating cycle independent of the moon.

The Romans initially followed a different system entirely. For centuries, Roman civil life revolved around an eight-day market cycle. But as astrology from the eastern Mediterranean spread through the Roman Empire, the seven-day planetary week became increasingly popular. Each day was associated with one of the seven classical planets.

How We Got to Seven Days

In 321 CE, Roman Emperor Constantine officially established the seven-day week in the Roman calendar, helping spread it across Europe. Some of those planetary names still survive in English today. Sunday honors the sun, Monday the moon, and Saturday Saturn. The names for the other weekdays reflect Anglo-Saxon names for Norse deities. Tuesday comes from Tiw, a Norse war god linked with Mars. Wednesday honors Odin (or Woden), associated with Mercury. Thursday derives from Thor, connected with Jupiter, while Friday honors Frigg, tied to Venus.

Not every culture embraced seven-day weeks, however. Ancient Egypt sometimes used 10-day cycles, while parts of West Africa followed four-day market weeks. Revolutionary governments also occasionally tried to reinvent the calendar. During the French Revolution, reformers introduced a 10-day week intended to break with religious tradition and make timekeeping more “rational.” (All the days and months were named after elements in nature.) Soviet officials later experimented with five-day and six-day workweeks in an effort to maximize industrial productivity; the days were even color-coded. Neither experiment lasted.

The persistence of the seven-day week is remarkable, considering how arbitrary the unit really is. Unlike days, months, or years, a week is fundamentally a human invention — one shaped by ancient sky-watchers and thousands of years of habit.

The Roman Workday Ended at Noon

The ancient Romans didn’t have clocks they could use to count the hours of the day. Instead, they kept track of the time using the position of the sun, and employed devices such as sundials to divide the day and night into 12 evenly spaced units called “hora” (hours). Since tracking the sun was the Roman citizen’s principal timekeeping method, the workday was structured around solar positions that were easy to measure with the naked eye, such as sunrise, noon, and sunset. For this reason, a typical citizen would usually start their workday at dawn, which marked the first “hora” of the day, and stop working at noon. This left the rest of the afternoon open for leisure, and citizens from all levels of Roman society would spend that time attending sporting events, theatrical performances, and the all-important public baths.

The Roman People Loved to Gamble

A love of gambling extended to all levels of ancient Roman society. Less-wealthy citizens would place bets on a wide variety of board games and dice games, which they played in taverns, city streets, and other public spaces, while the rich would build private gaming rooms in their homes. Romans would also frequently bet on the outcomes of gladiator fights and chariot races. (For the most part, only men were permitted to gamble, though women were allowed to participate in games of chance during special festivals.) Even the Roman emperors got in on the action. Rulers such as Augustus and Nero were known for their gaming habits, and for betting small fortunes on a single throw of the dice. Roman Emperor Claudius even had a custom-made carriage built with a gaming table so that he could gamble while traveling.

The Roman Forum Was the Center of Public Life

With its location right in the middle of the city, the Roman Forum was quite literally the center of everyday life in ancient times. It was where the typical Roman citizen could shop, talk, and find entertainment. It was also the site of most of the city’s public gatherings, the Roman courts of law, and the meeting place of the Roman Senate. What’s more, the forum housed some of Rome’s most important religious sites, including multiple temples dedicated to Roman deities. In other words, if you were a Roman citizen, chances were good that you’d be making frequent visits to the forum for everything from daily errands to grand citywide ceremonies.

There Was a Temple Where Citizens Could Go to Worship Caesar

One prominent temple in the Roman Forum was dedicated not to the worship of a mythological god, but to the former dictator of Rome, Julius Caesar. During the funeral games held in Caesar’s honor shortly after his assassination in 44 BCE, a comet appeared in the sky for seven days, which the Roman populace interpreted as a divine omen that Caesar’s soul had ascended to the status of divinity. This popular belief that Caesar had become a god was codified into law two years later in 42 BCE, when the Roman Senate officially declared him a deity. After this, a temple was built in the forum in Caesar’s honor. It even had an altar where Roman citizens would offer sacrifices to the deified leader, just as they would to supernatural Roman gods such as Jupiter and Saturn.

An Alternative Theory

Historical sources are vague when it comes to the tersorium — it seems that few Romans found it noteworthy enough to warrant a weighty text or treatise. This has caused some modern scholars to question the actual purpose of the tool. We know it was found in most public latrines, but was it used for the cleaning of numerous behinds or simply for scrubbing the latrine itself, much like a modern toilet brush? 

The greatest proponent of the latter theory is Austrian archaeologist Gilbert Wiplinger. He argues that the popular idea that Romans used the tersorium to clean their behinds is incorrect. Having reviewed ancient textual sources, including Seneca and Martial, he notes that none of them clearly describes the sponge-on-a-stick being used for personal hygiene, and that a more logical — not to mention less gross — explanation would be its use as a toilet brush.

So if the Romans didn’t clean themselves with the tersorium, what did they use? Having examined scraps of cloth in an ancient septic tank in Herculaneum (an ancient city preserved in Campania, Italy), environmental archaeologist Mark Robinson concluded that fabric scraps were likely used instead of a sponge. Another option was to use pottery shards, known as pessoi (Greek for “pebbles”). This may sound almost as bad as using a shared sponge, but these pottery pieces — which were readily available in ancient Rome — were specially selected, with smooth edges. 

The Romans likely had options when it came to bathroom hygiene — but whether that was in the form of a shared sponge-on-a-stick, scraps of fabric, shards of pottery, or a combination of all three (or more), it’s hard to know for certain. What we can say for sure is this: We should all be very grateful for toilet rolls and bidets.  

Armenia Was the First Country to Adopt Christianity as an Official Religion

Though modern-day Armenia did not achieve lasting independence until 1991, the country’s origins date back to around the year 2492 BCE according to Armenian mythology. In that year, an ancient Armenian warrior known as Hayk is believed to have defeated invading forces led by a Mesopotamia leader called Bel, which in turn saw what now encompasses modern-day Armenia fall under Hayk’s dominion. Many centuries later, Armenia made history by becoming the first country to adopt Christianity as its official state religion. Around the year 300 CE, an apostle named St. Gregory the Illuminator converted King Tiridates III of Armenia to Christianity, and it was made the official state religion in 301 CE. The newly formed Armenian Apostolic Church subverted the pagan ideology that once existed throughout the region, and it eventually became the country’s national church.

The First Recorded War Took Place in Present-Day Iran

The ancient kingdom of Elam, located in the southern region of modern-day Iran, contained settlements dating as far back as 7200 BCE. Millennia later, around the year 3200 BCE, the Proto-Elamite period began, marking the start of organized civilization throughout the region. Though few specifics are known about these early societies, what is known is that the region was the site of the first recorded war in human history. Around 2700 BCE, the Sumerian King Enmebaragesi led an attack against the Elamites, ultimately emerging victorious. Though there may have been conflicts before this, the battle — for which details are sparse — marks the earliest recorded account of a long-distance military campaign between opposing independent states.

The Oldest Surviving Anatomical Atlas Originated in China

In 1973, a seminal 2,200-year-old atlas of human anatomy written on ancient silk was discovered in south-central China, dating to the time of the Han dynasty (206 BCE to 220 CE) — making it the oldest surviving anatomical atlas ever discovered. Known as the Mawangdui medical manuscripts, these texts describe various “meridians” found throughout the human body, a term used to refer to arteries, blood vessels, and other internal elements. The Mawangdui texts also predate many other ancient Chinese texts related to acupuncture, suggesting that these early anatomical findings may have heavily influenced the science of acupuncture in the region. The artifact was uncovered in the tomb of a Han dynasty aristocrat named Xin Zhui (also known as Lady Dai), who was buried alongside copies of the medical texts in 168 BCE.

The First Dumps

As cities grew, some societies began to push waste farther away from the home. By about 500 BCE, the Athenians in ancient Greece had established what are often considered the first municipal dumps in the Mediterranean world. Laws required waste to be deposited at least a mile outside the city walls and banned throwing garbage into the streets.

Similar patterns appear elsewhere. In ancient Egypt, planned towns placed rubbish heaps beyond their walls, while in Mesopotamia and other regions, people concentrated refuse in designated pits, middens, and dumping grounds rather than scattering it.

But these systems were rarely tidy or consistent. Even in classical Athens and Rome — societies with laws governing sanitation — enforcement was uneven and waste still piled up in many areas. In Rome, property owners were responsible for cleaning the street in front of their homes, and while some recycling and scavenging took place, dumps outside the city grew steadily.

The Original Recyclers

Centuries before the “Reduce, Reuse, Recycle” slogan, many ancient societies routinely incorporated debris from everyday life — including broken pottery, ash, rubble, and organic waste — intro construction projects. Archaeologists have found that materials from demolished buildings and discarded goods were mixed into mud bricks, packed into earthen floors, or used as leveling fill.

In Pompeii, for example, large mounds of refuse outside the city walls were not simply trash heaps but staging areas. Materials such as plaster and ceramics were sorted and then brought back into the city to be reused in construction.

This kind of reuse was widespread and practical. Unlike today’s plastics-heavy garbage, ancient waste streams were dominated by organic and mineral materials — things that could be easily repurposed. Ash could stabilize surfaces, broken ceramics could be mixed into building materials to strengthen floors and walls, and even human and animal waste could be (and often was) used in agriculture as fertilizer or for dyeing and tanning.

From Trash to Ash

Another common strategy for ancient garbage disposal, in places such as the Andes and Mesoamerica, was burning. Fire reduced the volume of organic waste and helped control odors and pests. The resulting ash could then be reused: It was often spread over streets, incorporated into construction, or used in cleaning.

But burning trash wasn’t always purely practical. In many cultures, fire had ritual significance. Offerings to gods were often consumed in flames, transforming physical materials into smoke that rose skyward as messages to the heavens. In some cases, the line between disposal and ritual destruction blurred, with burning serving both functional and symbolic purposes.

The First Sewers

When human waste wasn’t just deposited nearby or collected for reuse, it was sometimes flushed away. About 4,000 years ago, the Minoans of Crete were among the first to dump their sewage into water. They developed remarkably advanced plumbing systems and what might be the first flush toilets. At the palace of Knossos, rainwater was collected and used to flush several toilets in the east wing, carrying sewage through ceramic pipes into underground channels. These systems even included manholes for maintenance — a strikingly modern touch.

In the Indus Valley, cities such as Mohenjo-daro and Harappa (both in modern-day Pakistan) built extensive drainage networks during their peak in the third millennium BCE. Houses had bathrooms and toilets connected to covered street drains, with carefully sloped channels and cesspits designed to prevent clogging. Wastewater flowed out of homes and into larger systems, helping to keep living spaces relatively clean.

Later, the Romans scaled these ideas up dramatically. The Cloaca Maxima, one of the earliest large sewer systems, carried enormous volumes of waste out of Rome and into the Tiber River. Public latrines and flowing water created a shared sanitation infrastructure — though not necessarily a hygienic one. These systems didn’t necessarily solve the problem so much as relocate it: Waste disappeared from sight and smell but often ended up contaminating water sources downstream.

Living With Waste — and On Top of It

Despite these varied strategies, one thing is clear: Ancient people lived much closer to their waste than most of us would tolerate today. Garbage accumulated in streets, between homes, and beneath floors. It was reused in buildings, dumped just beyond city walls, or flushed into nearby waterways. Even where sophisticated systems existed, they were limited by maintenance, scale, and an incomplete understanding of disease.

And yet, there is a crucial difference between ancient trash and modern waste. Most ancient refuse was biodegradable or inert. Food scraps decomposed, ash dispersed, and even broken ceramics eventually blended into the soil. That meant waste could be absorbed, repurposed, or transformed in ways that are far more difficult today.

In fact, many ancient cities were quite literally built from their own discarded past. Layer upon layer of debris became the ground beneath new construction — a process repeated across millennia. What began as refuse became real estate. It’s a reminder that trash has always been part of human life. What has changed is not the problem itself, but the materials we leave behind — and how long they stick around.

A Cemetery for the Elite

It’s clear that Stonehenge was closely associated with the dead — the collection of Neolithic cremated human remains discovered at the site is the largest in Britain. In 2013, archaeologist Mike Parker Pearson and his team excavated more than 50,000 bone fragments from 63 individuals buried at Stonehenge. Certain high-status artifacts found at the site, such as a mace head and what may have been an incense bowl, suggest that the people buried there were significant religious and political leaders, along with their families. The researchers also suspect that the burial ground could have been used by a single royal family over many generations. 

A Healing Center 

In 2008, two of Britain’s leading archaeologists and world-renowned Stonehenge experts, Timothy Darvill and Geoff Wainwright, proposed a slightly controversial yet compelling new theory: Stonehenge was a site of healing, like a prehistoric Lourdes. The key to their theory is the presence of bluestones at the site — the smaller stones that form the inner circle of Stonehenge. These stones came from the Preseli Hills in Wales, more than 150 miles away, where they were associated with healing springs believed to be imbued with mystical properties. It was because of their healing properties, Darvill and Wainwright argue, that people went to such great lengths to drag the stones all the way to Salisbury Plain. 

To support their claim, they point toward the large amount of bluestone chips scattered around Stonehenge, suggesting people had broken off pieces to heal themselves. They highlight one specific case, that of the “Amesbury Archer,” whose tomb was discovered near Stonehenge. Analysis revealed that the archer came from central Europe and suffered from a knee injury and infected jaw. He died around 2300 BCE, the same time the bluestones arrived at Stonehenge. Wainwright and Darvill speculate that he came to Stonehenge in search of healing. 

A Monument of Unity

The idea of Stonehenge as a place of worship has been around for centuries (albeit erroneously connected with Druids). Recent research, however, suggests that the site may have been a sacred gathering place of far greater significance than previously thought. 

In 2024, new analysis revealed a truly astounding discovery: The central, 13,200-pound bluestone at Stonehenge was not brought from Wales, but was dragged (or perhaps floated) to the site from the far northeast of Scotland, a distance of at least 466 miles. With this in mind, researchers at University College London and Aberystwyth University, led by archaeologist Mike Parker Pearson, proposed a new theory: Stonehenge may have been built to unite early British agricultural communities. 

Parker Pearson suggests that the large altar stone may have been brought all the way from a distant Scottish monument as a gift, or perhaps as a marker of political alliance or allegiance. If true, this would make Stonehenge a political monument as much as a religious one — a physical embodiment of unity among Britain’s diverse Neolithic communities.

While the full truth about Stonehenge may be lost to history, archaeologists continue to unearth tantalizing details about the monument’s purpose. And it now seems that Stonehenge was not limited to one specific role, but may have served a number of overlapping purposes, both practical and symbolic.

Advanced Plumbing and Sewage Systems

Perhaps the most impressive features of Indus Valley cities are the pioneering indoor plumbing and waste management systems that helped curb the spread of diseases. Virtually every home had an indoor washroom and latrine, with brick pavement floors packed tightly to prevent leaking and sloped to ensure proper drainage. Waste traveled through terra-cotta pipes that were routed to covered drain ditches that ran along city avenues and into an underground sewage system that flowed out of the city. Screens were installed at various areas for the collection of solid waste, while other points along the sewage network had holes and removable stones that allowed for inspection.

A millennium later, Rome also had an extensive underground sewer system, as well as a dedicated waste-management labor force and even a collection of public toilets for its citizens. However, the indoor plumbing structure that was enjoyed by just about every Indus Valley city-dweller was a luxury that was available only in Rome’s more expensive neighborhoods. 

A Society of Equals?

One of the major mysteries of the Indus Valley civilization is the dearth of surviving structures pointing to a clear ruling authority, such as a palace or royal tomb for a monarch, or a temple for a dominant religious organization.

The lack of such grand edifices matches up with other architectural features of Indus Valley cities: Homes, while differing in size, were not so drastically misproportioned as to highlight major discrepancies in wealth between residents. What’s more, public buildings such as the Great Bath were located in easily accessible areas that underscored the idea of communal sharing.

This has prompted some historians to posit that Indus Valley communities were organized by the principles of a heterarchy, with contributions coming from different groups of people, as opposed to the top-down demands of a hierarchy. And that could well have fostered a system of social equality that would have been unheard of in Rome, with its aristocratic class of patricians holding control in the early days of the republic, before power concentrated in the hands of an emperor in the imperial era.  

For all their achievements, the Indus people couldn’t stave off the demise that felled Rome and the other great cultures of antiquity; the civilization began to decline around 1700 BCE due to a combination of factors including climate change and dwindling trade. Nevertheless, this often-overlooked culture has received its belated due for being far ahead of its time, a testament to the impressive records it left behind even as more remain to be revealed.

Medieval Hair Care

Contrary to the perception that personal hygiene was lacking in the Middle Ages, people didn’t actually ignore their hair. Most medieval Europeans simply rinsed with water, while well-off households often made their hair cleansers out of ashes, egg whites, and herbs or flowers for fragrance. Combs were important for more than keeping up appearances: In a time of minimal hair-washing, they were trusty tools for removing dirt buildup and lice. 

Colonial Soaps

As Europeans arrived in the Americas in the 16th and 17th centuries, they brought their hygiene habits with them. Combs helped keep hair relatively clean and critter-free, but hair-washing was infrequent. When hair was washed, it was typically with water or homemade soap. Soap mixtures hadn’t strayed much from ancient formulations — animal fat and ashes — but by this time the soaps were boiled and set into cleansing bars. Enslaved people in early America adapted to the limited resources they had, using cornmeal and oils to clean the hair and scalp.

Throughout the 1800s, hair-washing practices evolved. In 1814, Indian-born entrepreneur Sake Dean Mahomed opened a spa in Brighton, England, offering Eastern-inspired treatments such as oil-based head massages. The popular service eventually became known as “shampoo,” an English take on the Hindi word champo. Mahomed’s treatments became beloved by clientele such as King George IV and King William IV, and he is often credited with introducing the idea of hair-washing as a dedicated ritual to the U.K.

Soapmaking continued to improve, and by the late 1800s, the brands Cuticura and Ivory were being sold not only for washing the body but also as shampoos for the hair. The turn of the 20th century saw a major leap in hair care when German chemist Hans Schwarzkopf invented a dissolvible powder shampoo in 1903. It didn’t take off in the U.S. right away; in 1908, an instructional article titled “How To Shampoo the Hair” ran in The New York Times.

Shampooing began to find popularity in America in 1909 with the launch of Canthrox shampoo, a powder that was dissolved in water, but it wasn’t until the 1920s that regular hair-washing became commonplace with the advent of liquid shampoos.

Ridley Scott’s Gladiator

Debate surrounding the gesture did not end there — to this day, historians argue about the meaning of the thumb sign in gladiatorial contests. In recent years, for example, Anthony Corbeill, a professor of classics at the University of Virginia, told Time that the commonly held belief about the thumbs-up gesture is incorrect. According to Corbeill, “Sparing [a gladiator] is pressing the thumb to the top of the fist and death is a thumbs-up. In other words, it’s the opposite of what we think.”

But widely held notions can be hard to shift, especially when Hollywood puts its full weight behind something. Ridley Scott’s hugely successful historical epic Gladiator cemented in the public consciousness the idea that the thumbs-up we use today came from ancient Rome. Gladiator was itself inspired by Gérôme’s “Pollice Verso”painting, which was shown to the director to convince him to make the movie. Scott in turn took some ideas from the painting, including the use of the thumb gesture, despite a lack of historical evidence for it. In the same way that “Pollice Verso” shaped public opinion regarding the thumbs-up sign in the 19th century, Gladiator reinforced the idea through the power of the modern-day blockbuster.  

A Wartime Gesture

Despite the persistent Roman gladiator narrative, the modern positive meaning of the thumbs-up gesture likely developed through different cultural channels over many centuries. Though the exact origins are unknown, historians believe the gesture gained widespread recognition during the 20th century, particularly in English-speaking countries. And the reason for its spread might be found in war. 

According to the Oxford English Dictionary, one of the first recorded instances of the thumbs-up gesture used to indicate approval occurs in the 1917 book Over the Top by Arthur Guy Empey, an American who served in the British army in World War I. In the book, he explains the thumbs-up sign as being “Tommy’s expression which means ‘everything is fine with me’” (“Tommy” being a slang term for a British soldier).

Another theory suggests the gesture was used by pilots to communicate with the person starting a propeller in early preflight checks. The gesture then became common among fighter pilots during World War II, who used it to indicate to the crew that everything was good and they were ready to take off. So, while the modern thumbs-up sign might not have come from the gladiatorial arena, it was likely popularized during the two largest conflicts of the modern age.