Why are subway walls tiled?

In the '70s, graffiti moved to subway cars

Unlike static walls, the silver cars moved throughout the city, like a canvas in perpetual motion. That made them highly desired by graffiti artists, especially because tagging them was considerably more difficult and, in turn, more impressive than a simple tag in an alley.

NYC's first subway was built largely in secret

In 1870, Alfred Ely Beach secretly tunneled under Broadway in 58 nights, disguising his pneumatic subway as a mail tube to fool Tammany Hall, the corrupt political machine that ran New York City. Nearly half a million New Yorkers rode it before politics, and a stock market crash killed the project.

The simplicity of immersed tube tunnels

Tunnels have traditionally bored holes through the earth below the water. On the other hand, immersed tube tunnels connect hollow, massive sections in trenches along the floor of the body of water. Each section is built on land, floated to the site, submerged, and connected. This method saves money by reducing expensive underground work, and it preserves an area's aesthetic appearance.

Tokyo's transparent toilets use smart, automatic glass to make cleanliness visible

Dubbed the Tokyo Toilet project, this initiative installs restrooms whose walls are transparent when empty, so users can see whether they are clean and safe. When they lock, they turn opaque for privacy. Beyond addressing two key anxieties (hygiene and security), the project lends a distinct architectural prestige to typically banal (and reviled) toilets.

Who cleans the London Underground at night?

The London Underground, also known as the Tube, services millions of people every day. After the transit system closes each evening, a crew of workers known as “fluffers” gather to clean the underground tunnels. This article sheds light on these unnoticed cleaners, covering the difficulties of their jobs and the bizarre things they’ve encountered, from ghosts to nesting pigeons.

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.

Many of Wright's buildings used radiant heating

Frank Lloyd Wright’s buildings weren’t just radical because of how they looked, but many of them also incorporated stunning technological innovations. Radiant heating is one of Wright’s most popular heating systems, offering the comfort of walking on warm floors on a cold day.

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

How the 'Wallace & Gromit' stop-motion animators nearly ran out of clay

The makers of hit claymation films like "Chicken Run" and "Shaun the Sheep" require a highly complex, waxless recipe for the clay used to create their familiar characters. When clay producer Newplast went up for sale, the studio had to prepare to run out of its beloved material. Luckily, a suitor purchased the company, keeping the clay production alive.

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

Take a look at Wall Street’s architecture

From an architect’s point of view, the buildings on Wall Street help tell the story of the street itself. Take a walking tour of many of the major buildings on Wall Street, guided by architect Nicholas Potts.

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.

Roman concrete lasts longer than modern recipes—and even gets stronger

Today's concrete is made by binding ingredients, including chalk and silica sand, at high temperatures. Unfortunately, it weakens when exposed to salt water. This article explores how and why scientists are studying ancient Roman concrete, which grows stronger when exposed to salt water.

TikTok is changing the building trades

Plumbers, welders, and general contractors are meeting their customers on TikTok. This article delves into the growing group of tradespeople documenting their work (and advertising their services) on the popular app. The profiled workers are convinced this is the new way to sustain a life in the trades.

Sir David Attenborough suggested tennis balls be yellow

When you think of tennis, it's the iconic yellow ball, but tennis balls didn't always look like that. This Merchant of Tennis article explores the early tennis balls made from wood in the 1300s, to leather balls, to vulcanized rubber used in the late 1800s. Crucially, Sir David Attenborough worked to broadcast the 1967 Wimbledon Championships in color, leading to tennis balls changing from white to yellow.

How Scrabble got its name

Alfred Butts, a newly unemployed architect during the Great Depression, created Scrabble. But the game was named by James Brunot, who used the word to describe the most common action its players take part in: digging frantically.

Was the stone that sealed Jesus's tomb round or square?

Archaeologist Amos Kloner's survey of more than 900 Second Temple-era burial caves found only four with round, disk-shaped stones—all belonging to the very wealthy. The other 98-plus percent used square, cork-shaped stones, suggesting the popular image of a wheel rolled away from Jesus's tomb is probably a later artistic invention. The Greek verb translated as "rolled" can also mean "moved."

Spanish Colonial Revival favors red clay roofs, white stucco, decorative ironwork

The style recalls the motifs of structures in both Europe and in colonial Spain. Beyond clay roofs and stucco, the design also showcases arches and arcades, painted tiles, towers, and more.

Why is there an archaeologist in my trash can?

Archaeologists have always been interested in rubbish—sites such as waste heaps, middens, and latrines can be some of the richest places to learn about the human past. But the type of rubbish we're leaving behind is changing, and much of it now...

Our kitchen designs are outdated.

Spread the love [ad_1] For decades, kitchens have been centered around the work triangle: the relationship between the refrigerator, stove and sink. But while that basic principle still applies, it’s…

Roman gladiator referees wore tunics and carried switches

Drawing on visual and textual evidence, a Roman social historian shows that referees were a constant presence in gladiatorial combat. Rather than armor, they wore striped tunics and used long switches to signal fouls and control fights from a safe distance.

CT scanners at airports take images across energy bands to identify baggage contents

Old X-ray scanners' inability to distinguish between water and explosives has driven strict liquid bans and longer wait times through airport security. New scanners combine multi-angle images across the energy spectrum to determine an object's density and atomic composition for improved threat detection.

The wall separating East and West Berlin was a highly visible symbol of the Cold War

Built in 1961, the Berlin Wall physically separated East and West Berlin for nearly three decades—preventing East Germans from fleeing to the West. Its fall in 1989 signaled the collapse of communist regimes across Eastern Europe.

Cathode rays are beams of electrons that emit light when hitting a fluorescent screen

When these beams are emitted into an evacuated tube containing charged plates or a nearby magnet, deflections are observed due to the electron charge. In 1897, J.J. Thomson's calculations of this deflection led to his discovery of the subatomic particle.

How slugs helped soldiers during WWI

Slimy, squishy, slow-moving, and heroic? Slugs are land-dwelling mollusks known mostly for causing havoc in our gardens. But during World War I, slugs saved numerous soldier's lives as poison gas detectors. Learn how the unpleasant creatures earned their stripes in the battle to protect soldiers from chlorine, phosgene, and mustard gas as organic detectors.

The White House still has its original stone walls

Construction of the White House began in 1792 and continued even after 1800, when John Adams moved in. Despite being burned by British troops in 1814 and repeatedly renovated since, the White House's original Virginia sandstone walls remain intact.

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

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.

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

Mid-century modern graphic designers, known for their bright colors and bold lines in advertising, also found success with children's books.

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.

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.

Tattoos remain visible on your skin thanks to immune cells called macrophages

Some coin denominations have ridges etched on their sides, partly to prevent counterfeiting, in a practice called 'reeding.'

Coral reefs get their colors from zooxanthellae—microorganisms that line corals' digestive tracts and provide them with sugars in exchange for a home within this protective tissue.

Budweiser stores yeast derived from the original 1800s strain in a secret bunker, which only the Head of Yeast Management can access—not even the CEO

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

Before the current East Wing ballroom project, only two White House renovations in the past 100 years cost more than $10M.

Dorothy's famous entrance into Oz in 'The Wizard of Oz' relied on analog tricks, including a body double and sepia-toned paint, as much as it did on technology

Stars appear to twinkle because turbulence in the motion of molecules in Earth's atmosphere causes light to bend and wiggle rapidly on its way to the surface—a phenomenon called scintillation.

Fear or disgust related to clusters of holes and cracks, called trypophobia, may stem from evolutionary processes to help us avoid pathogens.

Watch this video that uses Lego bricks to explain how venture capital works.

Sunflowers have long been a symbol of nuclear disarmament because they can extract large amounts of radioactive cesium from soil.

While the first exchange-traded fund (a 'basket' of different assets that can be bought and sold on a stock exchange) in the US only launched in 1993, the global ETF market has grown to more than $10T in the short time since.

The 1987 Nintendo video game 'Stadium Events' isn't known for being particularly fun, but its scarcity has made it a highly sought-after item that has sold for up to $35K at auction.

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

Domino's Pizza's 30-minute delivery guarantee was responsible for the chain's 1980s surge, but it was discontinued after the company was found liable for delivery driver accidents.

Explore what it's like inside a patient isolation unit, used in situations such as treating a patient or suspected patient with Ebola.

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