The containment apparatus at Chernobyl is the world's largest movable metal structure

Watch a time-lapse of the installation of the New Safe Confinement structure

The world's largest movable metal structure was built to contain the radioactive material from the 1986 Chernobyl disaster, which had previously been confined within a structure built to last no more than 30 years. The new structure was slowly rolled along rails over the course of two weeks.

View a photographic timeline of the building of Chernobyl's containment structures

The first structure—built to last 20 to 30 years—served as a covering for the exploded reactor and was built from about 16 million pounds of steel. In 2016, a new containment shell was constructed nearby and rolled onto the previous structure before being finalized in 2019.

Watch a visualization of the construction of Chernobyl's sarcophagus

Built to contain the remains of Reactor 4 after the nuclear disaster, the "shelter structure" was constructed from about 400,000 cubic meters of concrete—enough to fill 160 Olympic-sized swimming pools. Construction required vehicles and cranes modified with special shielding to protect workers.

The Chernobyl exclusion zone remains a region restricted to public access

It now spans beyond the initial 30-kilometer radius around the nuclear plant to include surrounding areas found to have significant radioactive contamination. Aside from a handful of elderly self-settlers, permanent residency is banned, and access remains tightly controlled due to lingering radioactive contamination.

The 'Elephant's Foot' in Chernobyl is part of the largest documented mass of corium

The nuclear disaster produced around 200 tons of nuclear fuel that mixed with the surrounding melted reactor core materials. As of 2025, corium has been naturally formed four other times in history: once during the Three Mile Island accident and three times at the Fukushima Daiichi plant disaster.

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.

Russia's invasion of Ukraine has destabilized safety and oversight at Chernobyl

Russian forces cut power and disabled monitoring of the decommissioned nuclear power plant in 2022, endangering operators at Chernobyl. In February 2025, a Russian drone struck the confinement structure—part of broader efforts to pressure Ukraine's energy infrastructure—punching a hole in the containment shell.

As of 2025, CERN is the world's largest particle physics laboratory

Founded in 1954, the European Organization for Nuclear Research's laboratory is located near Geneva, Switzerland, and more than 10,000 scientists from more than 100 countries visit its facilities each year. Its largest tool is the Large Hadron Collider, a 27-kilometer-long tunnel that accelerates protons to near the speed of light.

In 1984, Operation Smash Hit intentionally crashed a 239-ton train into a nuclear waste canister at 100 miles per hour to prove the canister's safety, which remained completely intact and lost just 0.29 of its 100 pounds of pressure.

For decades, the US has considered building a permanent nuclear waste repository

All nuclear waste would have been stored at Nevada's Yucca Mountain, but the Obama administration indefinitely stalled the project after intense community backlash. Spent fuel is now stored at more than 80 locations in 36 states, raising safety concerns.

Biosphere 2 is the largest Earth science experiment ever built

The vivarium—an enclosed system including animals and plants—is sealed from below with 454 metric tons of stainless steel liner and includes an ocean habitat with more than 700,000 gallons of seawater. B2 is visited by 100,000 people yearly, including more than 10,000 K-12 students.

Water acts as a coolant and a moderator of nuclear reactions in reactors

Nuclear reactions within a containment structure boil water into steam, which drives a turbine that generates electricity. This water is then recirculated via pumps back into the containment structure to repeat the process, with reaction rates lowered by the insertion of control rods that absorb neutrons, which trigger reactions.

The Tsar Bomba was the most powerful nuclear weapon ever tested

In 1961, the Soviet Union detonated AN602—known as the Tsar Bomba—the largest nuclear explosion in history. Newly released Russian footage starkly illustrates the unmatched destructive power of this nuclear weapon.

The canal became the first use of lock-and-lake system at a massive scale

The system centered around Gatun Lake, the largest human-made reservoir at the time, and two massive concrete locks that helped raise the ships 85 feet from sea level to the lake surface. The excavation was also the largest earth-moving project at the time, moving 240 million cubic yards of soil.

The high-tech mechanisms of the Roman Colosseum

The Roman Colosseum is one of the most iconic amphitheaters in the world and still partially stands today. Aside from its sheer size, the arena was equipped with some of the most high-tech engineering from the classical world, including sophisticated lifts, a huge retractable awning, and an underground network of tunnels, elevators, and trapdoors.

Black Rock City is a remarkable portable town

While Burning Man hosts many impressive and unique architectural feats, these buildings also have notable issues of safety, accessibility, and reliability.

An 800-ton shake table is the world's largest earthquake simulator

After the 1995 Kobe earthquake killed over 6,000 people, Japan created E-Defense to reproduce the force of earthquakes and test them against structures as tall as 10 stories, leading to changes in Japanese building codes to reduce collapse rates.

Modern landfills use layered liners, leachate systems, and gas monitors to safely contain waste

Today, landfill engineering is far more complex than a hole in the ground, which was largely the system cities used less than a century ago. This video explains how it actually works.

As of 2025, the Factory of the Future 1.0 is the world's largest 3D printer

Housed at the University of Maine, the machine incorporates AI and can utilize bio-based materials to construct homes exceeding 3,000 square feet in size. Homes made from these materials are fully recyclable, as their components can be deconstructed, ground up, and reused as raw materials for printing.

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

The Russia-Ukraine conflict is the largest ground war in Europe since World War II

The Russia-Ukraine war began on Feb. 24, 2022, when Russian forces launched a multi-front invasion. The conflict has become Europe's largest ground war since World War II, reshaping global security, energy markets, and alliances.

Wildfire containment requires trenches, natural barriers, or burned land

Containment refers to creating a perimeter around a fire that it is unlikely to spread beyond. However, full containment does not mean the fire is extinguished. Strong winds can cause fires to jump containment lines, including 10- to 12-foot-wide trenches or thin rivers.

The hand-dug 'Big Well' of Greensburg, Kansas

Inside the most crowded place on Earth

Once the densest place on Earth, Kowloon Walled City was a chaotic labyrinth of stacked homes, hidden corridors, and thriving underground life.

See the world's longest glass-bottom bridge in China

China's Huangchuan Three Gorges Scenic Area sports the world's longest glass-bottom bridge, spanning over 1,700 feet. Designed by the Architectural Design & Research Institute of Zhejiang University, it stands 660 feet above the Lianjiang River. The bridge features bright red towers, an 29-foot-wide deck with three layers of thick glass, and can support 500 people. The bridge surpassed the previous record-holder, a 1,600-foot bridge in Hebei province.

An electric pipe organ in Germany is playing a song for 639 years

Created by composer John Cage, the Halberstadt organ first began playing the piece in September 2001, and has since made only nine chord changes. The device within a medieval church utilizes compressed air to play continuous tones. The next chord change is scheduled for August 2026.

Faraday cages protect enclosed objects by redirecting electrical currents

Constructed from conductive materials, the cage allows electrons to distribute themselves evenly throughout its surface and travel to ground, keeping the interior neutrally charged and preventing any internal electricity. The same principle blocks electromagnetic waves by redirecting the electric field component, preventing telecommunication signals from entering the apparatus.

How fusion—which releases energy when two lighter atoms combine to form a heavier atom—differs from fission

Massive 3D printers have been used to build homes by stacking layers of 'concrete toothpaste,' a fire-resistant material that effectively insulates against outside noise.

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

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

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

The US Constitution is widely regarded as the longest-standing written national constitution still in force—see how it has influenced rights worldwide.

The syncytiotrophoblast is the outer layer of the placenta and the largest human cell, spanning an area about twice that of a king-sized bedsheet.

Watch how deep-sea mining equipment collects and processes polymetallic nodules—metal-rich, potato-shaped rocks—from the ocean floor and creates environmentally damaging plumes of sediments.

For centuries, Niagara Falls has been a magnet for daredevils seeking to conquer one of nature's most powerful wonders, with its 200-foot drop and water rushing at 32 feet per second with 280 tons of force.

Discover the catastrophic consequences of a failure of the US electrical grid—something that is more likely than many Americans think.

The first image of a black hole was captured by creating an Earth-sized virtual observatory from a network of eight radio telescopes.

Double world record holder Hunter Ewen helped conquer his fear of balloons, called globophobia, by training to win Guinness World Record titles for balloon inflation.

Iran's Revolutionary Guard Corps is independent of Iran's regular army and is one of the most powerful and influential military-political organizations in the Middle East.

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

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.

Astronauts have repaired genetic damage in space using CRISPR—a molecular tool that can make precise changes to DNA and is used in single-celled organisms to attack invasive viruses.

Sony set the standard for cylinder-shaped batteries when it repurposed manufacturing equipment used to make rolls of magnetic recording tape.

A 2019 Facebook event called on attendees to "Storm Area 51, They Can't Stop All of Us," resulting in countless memes, the creation of a music festival, and eventually the arrests of those who did try to approach the area.

In 2026, Finland was named the world's happiest country for the ninth consecutive year based on its wealth, social safety network, and high life expectancy, among other factors.

Poison ivy will likely become both larger and more resilient due to climate change.

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.

See photos of Meteora, a mountainous site in central Greece, home to 14th-century monasteries perched atop soaring outcroppings.

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