1

Brooklyn Bridge, New York: A family affair with an undersung heroine

Designer John Roebling died from tetanus after his foot was crushed during the initial survey in 1869, leaving his son, Washington, to complete the project. Then Washington developed debilitating "caisson disease" (the bends) from working in the underwater pressurized chambers, leaving him bedridden and barely able to speak. For the next eleven years, he directed construction from his apartment window through a telescope, while his wife Emily became his voice , learning advanced mathematics and engineering to communicate his instructions to the workers.

Emily Roebling essentially became America's first female field engineer, though she received no official title or recognition at the time. She walked the bridge on opening day in 1883, carrying a rooster as a symbol of victory—a moment that should have cemented her place in history but was largely forgotten until recently.

2

Golden Gate Bridge, San Francisco: They said it couldn't be built

Engineers insisted it was impossible: the water was too deep, the currents too strong, the fog too thick. Joseph Strauss, the chief engineer, was mocked by colleagues who called his design "Strauss's Folly." The Navy opposed it, claiming it would obstruct their ships. Environmentalists feared it would ruin the bay's natural beauty. Ferry operators lobbied against it, worried about losing their livelihoods.

Yet construction began in 1933, during the Great Depression, providing thousands of jobs when they were desperately needed. Strauss installed a revolutionary safety net beneath the bridge, saving nineteen men who became known as the "Halfway to Hell Club." Tragically, ten other workers still died when a section of scaffolding fell through the net near the end of construction. When it opened in 1937, the bridge was the longest suspension span in the world . Strauss died just one year after the bridge opened, worn out by the battle to build his "impossible" dream.

3

Sunshine Skyway Bridge, Florida: Rising from tragedy

On a foggy May morning in 1980, the freighter MV Summit Venture lost radar during a violent thunderstorm and slammed into the Sunshine Skyway Bridge. A 1,400-foot section of the bridge collapsed into Tampa Bay , sending six cars, a truck, and a Greyhound bus plummeting 150 feet into the water below. Thirty-five people died instantly. The only survivor was a truck driver whose vehicle teetered on the broken edge.

Rather than simply repair the damaged bridge, Florida decided to build an entirely new one. The new Sunshine Skyway, completed in 1987, features massive concrete "dolphins"—protective barriers designed to absorb ship impacts and prevent another catastrophe. The old bridge's remaining sections were converted into fishing piers, now popular spots where anglers cast lines into the same waters where so many lives were lost.

4

Tacoma Narrows Bridge, Washington - Galloping Gertie's fatal dance

From the moment the Tacoma Narrows Bridge opened in July 1940, it moved—undulating, twisting, and bucking in the wind like a living thing. This rhythmic, vertical bouncing reminded locals of a galloping horse, thus earning the bridge the nickname 'Galloping Gertie.' Engineers knew about the movement but considered it within acceptable limits. For four months, Gertie galloped along, becoming a tourist attraction and a source of local pride. Then came November 7, 1940.

In 40-mph winds, the bridge entered an aeroelastic fluttering that tore it apart in spectacular fashion. The only casualty was a three-legged black Cocker Spaniel named Tubby, left in a car by his owner, who fled on foot. Film footage of the collapse became required viewing in engineering schools worldwide. A new bridge opened in 1950 with crucial design changes, and in 2007, a parallel span was added.

5

London Bridge, Arizona: The bridge they bought by mistake

American entrepreneur Robert McCulloch bought London Bridge in 1968 for $2.46 million and had it shipped, stone by stone, from London to Lake Havasu City, Arizona . Urban legend claims McCulloch thought he was buying the iconic Tower Bridge and was disappointed when his purchase turned out to be the relatively plain London Bridge. While McCulloch denied this, the story persists because it's too good not to be true.

The bridge was disassembled into 10,000 tons of granite blocks, each numbered and shipped across the Atlantic. Workers reassembled it in the Arizona desert like a giant jigsaw puzzle, creating a channel beneath it afterward to make it an actual functioning bridge.

6

Chesapeake Bay Bridge-Tunnel, Virginia: Engineering ambition gone mad

When engineers proposed building a crossing for the 17.6-mile-wide mouth of Chesapeake Bay, skeptics called it impossible. The crossing would need to accommodate massive naval and commercial ships heading to Norfolk, one of America's busiest ports, while also withstanding hurricanes and ocean storms. The solution was audacious: build a structure that would be partly bridge and partly tunnel, diving beneath the water at two points to allow ship traffic through .

The completed structure, opened in 1964, includes two mile-long tunnels, nearly 12 miles of trestle bridges, four man-made islands, and multiple high-level bridges—all exposed to the open Atlantic Ocean. It was immediately declared one of the "Seven Engineering Wonders of the Modern World."

7

Seven Mile Bridge, Florida Keys: Flagler's folly made real

Henry Flagler's dream of extending his railroad to Key West was called "Flagler's Folly" by critics. But Flagler, already wealthy from Standard Oil, was determined to connect the Keys to mainland Florida. Construction began in 1905, facing hurricanes, mosquitoes, brutal heat, and the challenge of building in water up to 40 feet deep. The worst disaster came in 1906 when a hurricane killed over 100 workers—mostly immigrant laborers, whose tragic deaths barely made headlines at the time.

The railroad finally reached Key West in 1912, a year before Flagler's death. For 23 years, it carried tourists and freight until the monster Labor Day Hurricane of 1935 destroyed much of the track, killing hundreds. Rather than rebuild the railway, the state converted the route into the Overseas Highway, with the Seven Mile Bridge becoming its centerpiece . The original bridge served cars until 1982, when a new parallel bridge opened.

8

Mackinac Bridge, Michigan: The bridge that refused to die

Dreams of a bridge between Michigan's Upper and Lower peninsulas dated back to the 1880s, but the five-mile strait seemed unbridgeable. The Great Depression killed early plans, and World War II delayed them further. By the 1950s, the project had died and been resurrected so many times that locals joked it would never happen. Then, engineer David Steinman took on the challenge, designing a suspension bridge that would span the straits despite brutal weather, thick ice, and deep water .

Construction from 1954 to 1957 employed 3,500 workers at its peak. Opening day in 1957 drew 50,000 people, and Governor G. Mennen Williams walked across alongside bridge workers. "Mighty Mac" became Michigan's symbol, though high winds remain dangerous—two vehicles have been blown off in separate incidents, leading to the bridge authority offering free transport for nervous drivers during storms.

9

New River Gorge Bridge, West Virginia: The bridge that became a party

When the New River Gorge Bridge opened in 1977, it was the world's longest single-span arch bridge and the highest vehicular bridge in the Americas at 876 feet above the New River. The structure cut a 40-minute winding drive down to one minute, transforming the region's economy. But locals decided the bridge's annual achievement deserved an equally monumental celebration. Thus "Bridge Day" was born: a festival where the bridge closes to traffic and people are legally allowed to BASE jump and rappel off it.

Every third Saturday in October, up to 200,000 people descend on the tiny town of Fayetteville (population 2,800) to watch hundreds of BASE jumpers leap off the bridge . It's the largest extreme sports event in the world and the only day of the year when BASE jumping is legal in the U.S.

10

Navajo Bridge, Arizona: The bridge to nowhere that changed everything

When the original Navajo Bridge opened in 1929, the closest town was 130 miles away, and the bridge spanned a remote section of the Colorado River in northern Arizona. Critics called it the "bridge to nowhere." But the bridge had a crucial purpose: it was the only crossing of the Colorado River for 600 miles, making it essential for anyone traveling between Utah and Arizona without taking a massive detour.

Over the course of decades, it became a vital link for Navajo Nation residents accessing healthcare, education, and commerce . It also opened the North Rim of the Grand Canyon to tourists, transforming the region's economy. By the 1990s, the original bridge couldn't handle modern traffic, so a parallel span opened in 1995. Rather than demolish the original, it was converted to a pedestrian bridge where you can look straight down 467 feet to the Colorado River.

1

What are bills made of?

Unlike other currencies, dollar bills are not made of paper or plastic. U.S. dollar bills are made from a special fabric blend composed of 75% cotton and 25% linen. This mix makes the bills extremely durable and resistant, and they can be folded about 4000 times before tearing.

2

What bills are valid?

Any U.S. dollar bill that was legally printed is valid, no matter how old, as American currency does not have an expiration date. While some bills might not be accepted by businesses of foreign exchange services due to their condition or if they are a discontinued version of the bill, the bills themselves are still valid, and American banks will accept them, though they might take them out of circulation.

3

American leaders

Five bills have a depiction of an American president. The exceptions are the $10 bill, with Alexander Hamilton on the front, and the $100 bill, with Benjamin Franklin. The $1 bill, depicting George Washington, is extremely symbolic: several elements are repeated 13 times as a nod to the thirteen colonies, and it showcases the Bald Eagle and the Eye of Providence as a sign of God watching over America.

4

A change in size

Did you know that dollar bills used to be so big that they were nicknamed "horse blankets"? Original dollar bills were 7.4 × 3.1 inches. In 1929, the Treasury Department reduced the size of bills to 6.14 × 2.61 inches to reduce production costs and materials. Old bills, though still valid, are worth much more as collector items.

5

Uniformity

Besides their value and design, all dollar bills have the same size (6.14 × 2.61 inches), color, and weight (1 gram) , which sets American currency apart from other countries where bills of different values are differentiated by size, color, or both. Why doesn’t the U.S. implement differences among bills? The cost of adapting vending machines, bank drawers, and ATMs to new bill sizes would cost billions of dollars.

6

Hard to copy

Originally, dollars were not green, but black. As time passed, green ink was favored, as it was cheap and did not fade as much as black. The new color also prevented people from using black-and-white cameras to create counterfeit money. Currently, dollar bills are predominantly green, but newer versions also include extra colors, such as pink, orange, or purple.

7

A $100,000 bill?

Have you ever seen a $500 or 1,000 dollar bill? What about a $100,000? Up until 1945, the U.S. Treasury printed $500, $1,000, $5,000, $10,000, and $100,000 notes , in addition to the values currently in use. These higher-value notes were mainly intended for bank and government use, but were sought by criminals as they made it easier to hide large amounts of money. Even though they were officially discontinued in 1969, these notes are still valid, though rare, and they have a high worth as collector's items.

8

No numbers

Unlike bills, American coins have different sizes and colors related to their value. Originally, gold, silver, and copper were used for coins, but modern coins are made of copper, zinc, or nickel. Besides their size and design, the value of each coin is printed in letters, not in numbers , alongside depictions of American presidents.

9

Liberty for all (the coins)

By law, all American coins must include six specific details : the word ‘Liberty’, the name of our country, the national motto "In God We Trust", the oldest American motto "E Pluribus Unum", the value of the coin, and the year. Each coin also includes a mint mark that shows where it was made: "P" for Philadelphia, "D" for Denver, "S" for San Francisco, and "W" for West Point.

10

A global currency

The American dollar is one of the most powerful currencies in the world, acting as a backbone for international trade and finances. It is estimated that two-thirds of the physical dollars in circulation are outside American territory. Besides the U.S. and its territories, eight sovereign nations have the U.S. dollar as their official currency, with several more accepting it as legal tender.

1

There's an unexplained billion-year gap

Look closely at the canyon walls, and you'll notice something strange: a clean, sharp line where ancient rock simply stops, and a much younger layer begins directly above it.

This geological puzzle is called the "Great Unconformity," and it represents over a billion years of rock layers that are simply absent , as though that stretch of time never happened. In some spots, rock dated 1.8 billion years old sits directly beneath rock that is only 520 million years old. Where did the missing billion years go?

The leading theory involves the violent breakup of an ancient supercontinent, but scientists are still piecing it together.

2

During the Cold War, it hid a nuclear fallout shelter

During the Cuban Missile Crisis in 1962, the U.S. government converted part of the Grand Canyon Caverns into a fallout shelter. This dry cave system, more than 200 feet underground, was stocked with enough food and water to sustain 2,000 people. Naturally, it was never occupied, and the supplies were never used.

The caverns have since been transformed into a tourist attraction, with organized tours winding through the same underground chambers that were once intended as a refuge from nuclear war. You can even book a night's stay there.

3

The Federal Aviation Administration was founded after a crash over the canyon

In 1956, two commercial passenger planes collided in midair over the eastern Grand Canyon, killing all 128 people on board both crafts. Rescue teams struggled to reach the wreckage deep inside the canyon, and the extreme heat of the crash had caused the planes' aluminum to fuse with the bedrock. There were no survivors.

The disaster exposed a terrifying truth: the U.S. air traffic control system was dangerously outdated, relying on pilots' visual estimates and rough guesswork from controllers , with no way to separate fast-moving aircraft from slow ones, or instrument-flying planes from those navigating by sight. Congress responded by passing legislation that created both the Federal Aviation Administration (FAA) and the National Transportation Safety Board.

4

A hoax suggested that an Egyptian civilization had lived there

In 1909, the Arizona Gazette reported that an explorer named G. E. Kinkaid had discovered a vast underground citadel inside the canyon, filled with artifacts linked to ancient Egyptian civilization. He even claimed the expedition had been funded by the Smithsonian.

This story described hieroglyphics on the walls, mummies in the chambers, and relics pointing to a direct connection with the Egypt of the pharaohs. It was incredibly detailed, and it was, of course, a hoax. No evidence for any of Kinkaid's claims ever surfaced.

5

Fewer than 100 people have ever hiked its full length

Among the few people who have completed the through-hike of the Grand Canyon is Jen Hogan, the first woman to accomplish it, finishing her journey in 2021–2022.

It’s a full 800-mile length below the rim. The route involves extreme heat, flash floods, near-impassable areas, and stretches with no water or trail whatsoever. Around 60 or 70 people have reportedly accomplished it. This makes it one of the most exclusive feats on Earth.

6

The Grand Canyon's rocks predate dinosaurs entirely

Visitors scanning the canyon walls for fossils are often surprised to learn they won't find any dinosaur bones here. The rock layers of the Grand Canyon are simply older than dinosaurs. This fact alone can be shocking: staring at its walls means staring at marine fossils from as far back as 1.2 billion years ago. Some of its caves hold the remains of ancient mammals. The canyon is a window into a world that existed long before the dinosaurs, when the land that is now Arizona lay beneath a shallow sea.

7

The park is bigger than Rhode Island

Numbers alone rarely capture the Grand Canyon's scale, so here's a different approach. Rhode Island covers about 1,214 square miles, and the Grand Canyon National Park spans 1,904 square miles.

The canyon's depth exceeds four Empire State Buildings (which is 1,454 feet) stacked on top of one another. That’s 6,093 feet at its deepest point.

8

But it's not the deepest canyon on Earth

For all its grandeur, the Grand Canyon does not hold the depth record. Pictured above, the Yarlung Tsangpo Grand Canyon in Tibet, China, plunges to 17,567 feet, which is nearly three times deeper. Carved by the Yarlung Tsangpo River as it cuts through the eastern Himalayas, that canyon is so remote and extreme that it remained largely uncharted until the late 20th century.

9

It is home to a pink rattlesnake found nowhere else on Earth

The Grand Canyon Pink Rattlesnake has a pinkish-red coloring that matches the canyon's own distinctive rock walls so closely that it's nearly invisible. It is found nowhere else in the world. Officially classified as Crotalus oreganus abyssus , it has darker diamond-shaped markings along its back that deepen the camouflage further.

10

There's a village at the bottom: Supai Village

For over 1,000 years, the remote village of Supai has been home to the Havasupai Tribe, the People of the Blue-Green Waters. It is located an eight-mile hike from the rim, but sits roughly 3,000 feet deep inside the Grand Canyon.

The U.S. Department of Agriculture has called it the most remote community in the contiguous United States, and it has no automobiles and no road access. The only ways in are on foot, by mule, or by helicopter. It is also the only place in the United States where the postal service still delivers mail by mule train.