1

The Beale Ciphers - Virginia

In the early 1800s, three coded papers surfaced, said to reveal the location of a hidden treasure in Virginia . Only one cipher (the second) has been partially decoded using the Declaration of Independence, pointing to a stash of gold, silver, and jewels.

Treasure hunters and cryptographers have tried for decades to crack the remaining ciphers. Yet, so far, no one has succeeded.

2

The Georgia Guidestones - Georgia

Erected in 1980, the granite monument carried inscriptions in multiple languages , laying out guidelines for humanity’s future. The massive slabs earned the nickname "America’s Stonehenge."

The mystery lies in who commissioned it. The sponsor used a pseudonym and never revealed their identity. Too bad they were destroyed in 2022 after being damaged by an explosion.

3

The "Wow!" Signal - Ohio, 1977

One night in 1977, Ohio State University’s Big Ear telescope picked up a deep-space radio burst lasting 72 seconds . Astronomer Jerry Ehman circled it and wrote "Wow!" beside the data.

The signal has never been definitively explained. Whether it was a passing comet, a reflection, or something else, no one knows.

4

Roanoke Colony’s "CROATOAN" - North Carolina

In the late 1500s, settlers on Roanoke Island disappeared, leaving only the word "CROATOAN" carved on wood . Their fate remains one of the earliest American mysteries.

Some think they merged with local tribes, while others suggest they relocated. Without proof, the vanished colony remains a puzzle historians love to revisit.

5

The Taos Hum - New Mexico

Since the 1990s, some residents of Taos report hearing a low, steady humming sound . It’s described like a distant diesel engine idling in the desert.

Some studies suggest it may be related to low-frequency industrial noise or tinnitus in some individuals. The reality is, scientists have studied the phenomenon but haven’t pinned down a cause.

6

Marfa Lights - Texas

Out in West Texas, glowing orbs have appeared on the horizon for generations . They shimmer, split, and move in ways that seem inexplicable.

Tourists flock to Marfa hoping to catch a glimpse. Some suggest car headlights or atmospheric tricks, but the mystery remains.

7

Bloop-Like Ocean Sounds - Pacific Ocean

In the 1990s, NOAA hydrophones picked up a booming, low-frequency sound in the Pacific Ocean . Nicknamed "the Bloop," it was louder than known whale calls.

Theories ranged from icequakes to giant sea life. NOAA later concluded the sound was likely caused by large icequakes from Antarctic ice breaking apart.

8

The Upton Chamber - Massachusetts

Hidden in Massachusetts is a stone tunnel leading to a small underground chamber . Its age and purpose are still debated.

Some believe it was a colonial root cellar, while others argue it predates settlers entirely. Without records, the chamber remains an enigmatic piece of New England history.

9

America’s Stonehenge - New Hampshire

This site features stone walls, chambers, and standing slabs . Some argue it was built by Native Americans, while others see evidence of pre-Columbian visitors.

While some alternative theories suggest ancient origins, most archaeologists believe the structures are from the colonial-era. Whatever its origin, it’s a fascinating stop for curious travelers.

10

The Great Serpent Mound - Ohio

In southern Ohio lies a massive prehistoric earthwork shaped like a winding serpent . Stretching over 1,300 feet, it curves and coils across the landscape in striking detail.

Scholars agree it was built by Indigenous peoples, but its purpose is unclear. Some suggest it was a ceremonial site or calendar, while others see cosmic symbolism.

11

The Blythe Intaglios - California

Etched into the Colorado Desert, these giant figures depict humans and animals , some over 170 feet long. They’re best seen from the air, raising questions about how and why they were made.

Created centuries ago by Native Americans, their exact age and purpose remain uncertain.

12

Judaculla Rock - North Carolina

This large boulder is carved with hundreds of mysterious petroglyphs . Shapes, lines, and symbols cover its surface, their meanings long lost to time.

The Cherokee connect the markings to Judaculla, a legendary giant. Whether the rock was a sacred site, a map, or something else, the exact meanings of many carvings remain unknown.

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.