Who cleans the London Underground at night?

The archaeological sites uncovered through London's Crossrail Project

The Crossrail Project is an underground train system in London, which saw 26 miles of new tunnels created over more than a decade. The project provided unique access to long-buried layers of London's history, and a massive parallel archaeological excavation took place.

Why are subway walls tiled?

In the early days of subway tunnels, architects needed to deal with dirt and moisture and make the cavernous stations less dank and dark. Ceramic tiles were easy to clean, and their glossy, bright finish helped illuminate the cave-like areas.

Reflections from Ben Giles, history's greatest stain remover

Starting out as a freelance window cleaner, the British cleaning legend started taking on jobs cleaning out people's garages and shacks. He soon realized people would pay top-dollar to have their worst messes cleaned up by someone else.

More than 500,000 people worked to contain Chernobyl's fallout

The group—collectively referred to as "liquidators"—included firefighters, military troops, miners, engineers and sanitation crews. Beyond clearing radioactive debris and performing decontamination work, they confined radioactive material to prevent its spread into groundwater.

The sewage of New York City

Residents of the five boroughs of New York produce 1.3 billion gallons of wastewater everyday. Seventy miles of sewer pipes, first built in the mid-1800s, feed the sewage to 14 wastewater treatment and recovery plants where the waste is treated back to viable, drinkable water. See what shouldn't go down the toilet here.

Disney World's Magic Kingdom includes an underground utilidor

Walt Disney viewed everything happening in his parks as a performance and didn't like it when that performance was disrupted by necessary aspects of the park's maintenance, like trash collection. With Florida's Disney World, the company corrected that problem by building a massive area underneath the park to be used as a "backstage."

What it takes to guard the Tomb of the Unknown Soldier

Sentinels who guard the Tomb of the Unknown Soldier in Arlington, Virginia, must do so around the clock, year-round, no matter the weather. They're also a select few: Only 735 have been permitted to serve since 1958. This documentary explores the history of the role and the strict requirements it takes to fill it.

The myths around London's tiniest sculpture

The Philpot Lane mice have been considered London's smallest sculpture for decades, delighting visitors and locals alike. But there's a common story told for why the unusual sculpture—which features two mice fighting for a piece of cheese—was placed there, saying it commemorated the death of a construction worker fighting over a lunch in the 1800s. The author of this article argues the evidence for such a story is lacking. Dive into the obscure history here.

Broadway employs tens of thousands of people in various roles

While we often just think of the actors and directors who take top billing, Broadway productions operate as distinct businesses employing numerous people in various roles: stage managers, sound designers, house managers, ushers and more.

In 1971, a $35 ferret helped clean the Fermi National Accelerator Laboratory

Lacking cleaning robots, Fermilab scientists purchased a ferret named Felicia when metal slivers obstructing accelerated particles were identified. They trained her to run strings through vacuum tubes more than 90 meters long, and cleanser-dipped swabs were then tied to the strings and pulled through to remove the debris.

Fire engines are among the most complex vehicles on the road

These vehicles are purpose-built to carry water, foam, hoses, ladders, and lifesaving equipment to a scene in minutes. This animated video pulls apart every system inside a pumper truck, showing exactly how the machinery that fights fires actually works.

Cerebrospinal fluid flushes waste from your brain during sleep

Recent research suggests a nightly brain cleanup as an important purpose of sleep. Brain waves have been observed to work in lockstep with the brain’s blood flow and cerebrospinal fluid flow, allowing for a cleansing tide that washes away toxic waste.

The 'chief usher' manages the White House and a staff of roughly 100 people

Tracing back to 19th-century household roles, the chief usher is now the White House's general manager—overseeing renovations, maintenance, food service, budgets, and employees who run the daily operations of the complex.

Labor unions, explained

The weekend is one of many benefits shaped by labor unions. These organizations, representing millions of workers, have influenced much of modern work life, from wages to safety standards. With roots stretching back to the 18th century, unions have long been at the center of change in labor rights.

Explore the 2025 Uber lost & found index

A chainsaw. Ten live lobsters. A mannequin head with human hair. These are just a few curious items passengers left behind in Ubers this year, according to Uber itself. Uber is among the largest gig economy platforms in the US, with a valuation of roughly $150B as of 2024.

A day in the life of a leafcutter ant

Among the fascinating world of insects, leafcutter ants form some of the most complex and dynamic social ecosystems. All part of an effort to keep a colony alive, worker ants toil tirelessly, dragging bits of leaves and vegetation back to their...

Newspaper delivery people, trash collectors, and more: who to tip and how much

The suggested holiday tip amount for garage attendants is between $10 and $50, whereas the suggested holiday tip amount for doormen in apartment buildings is between $25 and $100 each.

How often should you clean your water bottle?

Experts say a daily wash of a high-use bottle is key to keep away unwanted bacteria and odors. For a good clean, use water—as hot as 140 degrees Fahrenheit—mixed with soap, swirling the mixture in the bottle before letting it sit for 20 minutes. Learn more tips with this quick overview.

Transit is funded through a three-tier system, and the federal government is the smallest piece

In 2019, the federal government covered about one-sixth of the $79B spent on public transit. States and localities make up the rest. About 85% of all transit trips are taken by bus or heavy rail, and nearly 4 in 10 US transit trips occur in the New York City metro area.

Money 'mules' don't always know they are laundering money

Money mules are anyone who receives money in a laundering scheme and then sends it forward, either to another company or to a financial institution. While some money mules—often called smurfs—actually work with criminals laundering money, getting someone to receive and then send money has become a popular scam.

Farm animals help maintain the grounds at Chicago's O'Hare International Airport

Since 2013, a herd of goats, sheep, and a donkey have grazed on the scrub vegetation at the airport. In the process, they also help keep out animals that can be dangerous for pilots, like coyotes.

In 1915, workers recovered a submarine-like vessel from the Chicago River, prompting fears of German espionage

Who are the people standing on the floor of the NYSE?

Today, not all of the trading is done on the floor of the New York Stock Exchange itself (computers help now), so it isn’t as chaotic as it once was. However, the NYSE is one of the few remaining trading floors where much active trading still happens in person.

A tube-and-diaphragm system tells gas pumps when to stop providing fuel

As long as air passes freely through a small hole at the end of the nozzle, the diaphragm is inflated, and fuel flows normally. Once fluid reaches the hole, the change in pressure from the difference in air and fluid densities collapses the diaphragm, which cuts the flow of gas.

A guide to the unspoken rules of British pubs

Pubs are more ingrained in British culture than in other parts of the world. This guide from CNN walks tourists through a taxonomy of the pub's many types, outlines proper etiquette, and sets realistic expectations. (Beware: Your beer might be warm.)

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

Watch David Attenborough’s documentary on bioluminescent creatures

Sea creatures can make their bodies glow to camouflage themselves by mimicking the appearance of the night sky as seen from underwater. Species without this ability can form a symbiotic relationship with bioluminescent bacteria or eat other organisms with relevant biochemicals.

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

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

Apollo astronauts left items in the moon's 'toss zone,' including golf balls, family photos, and bags of human waste, to make room for lunar rocks.

Watch the cumbersome, but necessary, precautions healthcare workers must take to care for and protect themselves while caring for Ebola patients.

To reduce wrinkles in clothing, research recommends gentle wash cycles with more water and tumble drying with smaller loads and longer times.

When you complete a CAPTCHA on a website to prove you are human, you may be unknowingly training algorithms for self-driving cars, whose systems require training data to help identify crosswalks, bicycles, and other outdoor objects.

The identity of the Tank Man in the iconic photo from the 1989 Tiananmen Square protests remains unknown and was possibly killed.

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.

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.

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

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.

The American cockroach is actually from Africa, an apparent hitchhiker aboard ships carrying enslaved people, with evidence suggesting the bug may have arrived in the New World as early as the 1600s.

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

The price of gas is a composite made up of several different factors, with the federal gas tax making up less than 20% of what drivers pay at the pump.

Hear about the 250-year history of the United States Postal Service, complete with some of its strangest deliveries, important innovations, and the figures that made it an American institution.

Dirty lightning is a thunderstorm created from friction between rising and falling flows of ash and smoke during volcanic eruptions.

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

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

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.

Georgia O'Keeffe's flower paintings are often assumed to be sexual, though the artist claimed she was simply interested in highlighting the beauty of flowers that most people neglect

Comedy legend Catherine O'Hara, star of 'Schitt's Creek' and 'Home Alone,' quit 'Saturday Night Live' after just one week to return to her old job.

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.

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.