1

Raven Rock Mountain Complex

Image: Ilagam

Did you know that in the 1950s, the US government carved out a secret underground city that could survive a nuclear attack? It’s called an "underground Pentagon", and very much like Area 51, it is one of the government's most classified projects.

This military complex and nuclear bunker is located near Blue Ridge Summit, Pennsylvania, 768 feet below the ground. It’s protected by 23.5 ft thick 30-ton doors built on top of springs to survive the shock from a blast. Raven Rock has five buildings with 15 floors big enough to live and work. The base has everything it needs to keep running, like a cafeteria, a barbershop, water generators, and even a medical center.

2

SubTropolis

Image: mwewering

Below Kansas City, Missouri, lies the world's largest underground business complex. SubTropolis is a structure located inside a mine north of the Missouri River. It was carved out of limestone some 135 to 185 feet underground and covers a total of 55 million square feet.

Kansas City Chiefs founder Lamar Hunt built this subterranean city in the 1960s. It has offices, storage space, and even factories. Over 1,600 people work here every day, largely because SubTropolis remains cool all year, making it an ideal location for businesses. Fun fact: some of Hollywood’s most beloved masterpieces are kept here, including the original film reels of Gone with the Wind and The Wizard of Oz.

3

Underground Atlanta

Image: Ronny Sison

Underground Atlanta is a historic spot in downtown Atlanta, Georgia. It was built in the late 1800s, right after the Civil War, as a commercial district centered around the railroad. In the 1920s, viaducts were built and the streets were raised, creating a second level of streets, buildings, and shops.

During Prohibition, the abandoned underground space served as the best spot for speakeasies and juke joints. For decades, people forgot about the hidden city, but in the 1960s, it was brought back to life as a fun place for music bars and nightlife.

4

New York City Subterranean World

Image: Photographer: unknown, Public domain, via Wikimedia Commons

Under America’s most populous city, there's a whole hidden world. For example, beneath Little Italy and the Public Library, there are secret vaults. Beyond the subway millions of people use daily, there is City Hall station, opened in 1904 and closed in 1945. It's a hidden gem with stained glass and mosaics that you can still visit by staying on the 6 train past the last stop.

But that’s not all! There are trading tunnels in SoHo and old cattle tunnels in the Meatpacking District. Also, in 1897, there were mail tubes built around the city to send letters between post offices that operated until the 1950s. Some of these underground spaces go as deep as 800 feet!

5

Permafrost Tunnel Research Facility

Image: Paxson Woelber

A large part of the land in the northern hemisphere is Permafrost, so it makes sense that there is a research facility specially built to study it. The Permafrost Tunnel in Alaska is the best place to learn about frozen soil that's over 40,000 years old.

The long tunnel was dug from 1963 to 1969 to study how to build and mine in frozen environments. Inside the facility, scientists study ice, ancient plants, and even bones from animals like mammoths. The tunnel shows different layers of earth, uncovering frozen ground from different time periods that help scientists anticipate what might happen as the world gets warmer.

6

The Greenbrier Bunker

Image: Alex Holzreiter

The Greenbrier Bunker in White Sulphur Springs, West Virginia, is a secret underground facility beneath a luxury hotel that has hosted numerous US presidents and famous guests. It was built during the Cold War to protect the US Congress in the event of a nuclear attack. The bunker was designed to house all 535 members of Congress and their staff for a long time.

This classified underground facility remained a secret until 1992, when a Washington Post article exposed it. Today, visitors can take tours to see special rooms, blast doors, and decontamination areas.

7

The Caverns

Image: jymy duhomme

Would you attend a concert underground? If you travel to Tennessee is totally possible! The Caverns, formerly known as Bluegrass Underground, is a very cool spot in Grundy County, Tennessee. Lying deep in a cave 333 feet underground, this concert venue with natural acoustics is the perfect place for live music.

People come from all over to hear a variety of performances, especially Bluegrass music. The Caverns can accommodate up to 1,200 people standing up and are equipped with state-of-the-art sound and lights. The cave's cool and quiet atmosphere makes the experience extra special!

8

Crystal City Underground

Image: Gustavo Alejandro Espinosa Reyes

Beneath the neighborhood of Crystal City, near Washington, DC, lies a network of shops, restaurants, and offices. It opened in 1976 and was designed to feel like an old shopping village with cobblestone streets and antique glass windows.

The underground space covers 150,000 square feet and connects several buildings. It's a popular spot for office workers and visitors, especially when the weather is bad. Unfortunately, in 2024, the shops closed, ending their retail era. Yet, the underground walkways and connections to the Metro remain open for pedestrians.

9

Los Angeles Prohibition Tunnels

Image: Alpha Perspective

In the 1920s, during Prohibition, people had to find ingenious ways around the restrictions on selling and consuming alcohol. That's why they built about 11 miles of underground tunnels right under Los Angeles.

Many of these subterranean sites are now closed, but you can still find a few hidden entrances around the city. You can even go on a tour to explore the tunnels and learn about their secret history.

10

Havre Beneath the Streets

Image: Đào Việt Hoàng

After a big fire in 1904 destroyed Havre’s business district in Montana, many shops moved underground. They used the old steam tunnels to stay safe from fires and bad weather. For years, the tunnels were busy with people and stores, such as saloons, drugstores, laundromats, and even a brothel. But today it is completely silent.

Fortunately, you can still visit what is left of this hidden city to see old shops and learn how people stayed safe and worked over 100 years ago. It's like going back in time!

11

Cheyenne Mountain Complex

Image: See page for author, Public domain, via Wikimedia Commons

One of the safest places in the world is right here in America, more specifically in El Paso County, Colorado. Hidden inside a mountain, Cheyenne Mountain Complex was built in the 1960s to protect the US military from nuclear attacks.

The bunker stands under 2,000 feet of solid Granite, making it super strong and safe. It was once the command center for NORAD (North American Aerospace Defense Command). The complex has blast doors that weigh 25 tons each and can withstand a nuclear blast. It also has its own power, water, and food supply. People could survive there for months!

12

Forestiere Underground Gardens

Image: Levi Clancy, CC0, via Wikimedia Commons

A Sicilian immigrant called Baldassare Forestiere spent 40 years digging and building a series of subterranean structures by hand in Fresno, California. Inspired by Roman catacombs and old wine cellars, he created around 65 rooms, tunnels, and courtyards to escape the hot summer sun.

The Gardens have fruit trees, grapevines, fishponds, and even a chapel. Some of the trees are more than 90 years old! Today, Forestiere Underground Gardens is a Historical Landmark you can visit if you want to discover a true underground paradise.

1

Clock change

Image: Jonathan Borba

US currency is full of symbolism, and the $100 bill is no exception. Since 1928, we have seen Independence Hall depicted on the back of this bill. But in 2013, it was redesigned, and one change stands out: the clock tower, which previously showed 4:10, now reads 10:30. Did you notice?

2

Jackie Kennedy’s choice

Image: Florida Memory

Jackie Kennedy played a key role in designing the coin that would feature the portrait of her ex-husband. When the U.S. Mint planned the Kennedy half dollar in 1964, she was consulted and provided input on various aspects of the coin, including its imagery and symbolism.

3

Not paper

Image: Giorgio Trovato

Although it is called paper money, our bills do not contain any paper at all. In fact, they are made of a blend of 75% cotton, 25% linen, and fine silk fibers embedded. This mixture is not random; it was specially chosen so that your bills can withstand everything: folds, wrinkles, stains, and even an accidental shower in the washing machine.

4

The unfinished pyramid

Image: Marek Studzinski

The one-dollar bill also has its secrets and details. On its back, you’ll find an unfinished pyramid, part of the Great Seal of the United States designed in the 1780s. Why unfinished? The pyramid has 13 steps, representing the original 13 colonies, and its incomplete form symbolizes the nation’s ongoing growth and expansion.

5

50% larger

Image: Bozhin Karaivanov

Before 1929, US banknotes were significantly larger, measuring approximately 7.375 x 3.125 inches. Today, collectors refer to these as "large-size" notes, sometimes even nicknamed "Horseblankets." In contrast, modern bills measure just 6.14 x 2.61 inches. The government decided to reduce the bill's size to cut production and design costs.

6

Andrew Jackson’s preference

Image: Giorgio Trovato

Andrew Jackson has been the face of the $20 bill since 1928, when he replaced Grover Cleveland. Ironically, Jackson was opposed to paper money. He didn't trust that form of payment, believing it could be easily manipulated. According to historians, the 7th U.S. President favored "hard money": gold and silver coins.

7

Alexander Hamilton’s portrait

Image: engin akyurt

Most portraits on US bills face left, with one exception: Alexander Hamilton on the $10 bill, the only one facing right (toward the viewer’s left). You might wonder why, but there’s no official explanation; it seems to have been simply a design choice.

8

"In God We Trust"

Image: rc.xyz NFT gallery

In 1956, Congress passed a law declaring "In God We Trust" the national motto, making it mandatory on all U.S. coins and banknotes. But this wasn’t its first appearance: the phrase first appeared in 1864 on the two-cent coin. Beyond faith, it also carried political weight, suggesting that God favored the Union during the Civil War.

9

The change that never happened

Image: Ryan Quintal

In 2015, the Treasury announced plans to redesign the $10 bill, stating that Hamilton's portrait would be replaced by that of an influential woman from US history. However, the change never happened. Why? Those years saw a surge in Hamilton's popularity thanks to the hit musical of the same name, leading the Treasury to backtrack on the replacement plan.

10

Criteria

Image: Live Richer

As is well known, not just any portrait can appear on US currency. But beyond historical significance, the figures on our bills and coins must meet other criteria you might not know: They must also be deceased and well recognized by citizens, ensuring that the people represented are familiar and meaningful to the public.

1

Patrick Henry: Give Me Liberty or Give Me Death!

On March 23, 1775, those gathered at the Second Virginia Convention debated whether Virginia should raise troops in preparation for armed resistance against Great Britain. Patrick Henry, a delegate from Hanover County, addressed the convention and argued that war had already started and the confrontation was inevitable , so an independent militia was necessary. Henry concluded with the famous declaration: "I know not what course others may take; but as for me, give me liberty or give me death!", a passionate appeal that helped secure the required votes.

2

Jimmy Carter: A Crisis of Confidence

Also known as the "malaise speech" (though Carter never used that word), this address by President Carter recognized a dire problem in 1979’s America: the people felt abandoned by the government in their time of need. The crisis was much more than an economic issue, and Carter wanted to know what everyday Americans thought and needed . In a speech shaped by conversations he had with ordinary Americans, Jimmy Carter declared that America’s crisis was " a crisis of confidence" that had struck at the very heart and soul of the nation.

3

Martin Luther King, Jr.: I Have a Dream

In one of the most iconic speeches in civil rights history, Martin Luther King Jr. addressed more than 200,000 people at the Lincoln Memorial in Washington, D.C., on August 28, 1963, during the March on Washington for Jobs and Freedom. Nearly a century after the Emancipation Proclamation, those freed from slavery were still not really free . After denouncing the laws that legalized racism and segregation, MLK expressed his wish for a free and unified America with a phrase that would go down in history: "I have a dream!"

4

Abraham Lincoln: The Gettysburg Address

Fought between July 1 and July 3, 1863, the Battle of Gettysburg was one of the bloodiest engagements of the American Civil War and was a decisive victory for the Union. Four and a half months later, President Lincoln delivered this speech on the battlefield, now a cemetery for more than 50,000 fallen soldiers. Lasting only about two minutes, Lincoln’s address reminded those present that it was the responsibility of the living to ensure that the sacrifice of the fallen would not have been in vain .

5

Sojourner Truth: Ain’t I a Woman?

Born into slavery as Isabella Baumfree, Sojourner Truth escaped after her enslaver failed to honor a promise to free her early under New York’s gradual emancipation law and uphold the New York Anti-Slavery Law of 1827. She later became an itinerant preacher and was involved in both the women’s rights and abolitionist movements. At the 1851 Women’s Rights Convention, she delivered a speech highlighting the double discrimination suffered by Black women . Even without full rights, white women received deferential treatment from men. Her phrase "Ain’t I a woman?" denounced that, while she had done all the things white women did and more, she was not considered worthy of respect because of her race.

6

Franklin D. Roosevelt: Pearl Harbor Address to the Nation

The bombing of Pearl Harbor by the Imperial Japanese Navy on December 7, 1941, marked the United States’ entry into World War II. The next day, President Roosevelt addressed Congress during a joint session, asking for a declaration of war. This address, famously remembered by its opening line—"Yesterday, December 7, 1941—a date which will live in infamy"— reinforced the idea of the attack as an unprovoked aggression that had resulted in over 2,400 casualties, both civilian and military, and appealed to patriotic sentiments. The speech attracted the largest live audience in American history (over 80% of the adult population) and resulted in Congress unanimously declaring war on Japan that same day.

7

John F. Kennedy: Inaugural Address

John F. Kennedy gave several memorable speeches during his presidency, but his inaugural address remains one of the most remarkable, and for good reason. According to accounts from his inner circle, the speech was meticulously crafted and reworked multiple times by Kennedy , who consulted the opinion of friends and advisors, and poured hours into making sure his first address as president would reflect the route he intended to take. As the youngest person elected to the presidency, Kennedy represented a generational change in the government. The central theme of his address was a call for civic responsibility and national service, an idea summarized in the address’s most memorable line: "Ask not what your country can do for you—ask what you can do for your country."

8

Frederick Douglass: What to the Slave is the Fourth of July?

A writer, orator, and statesman, Frederick Douglass was a major figure of the abolitionist movement. Born into slavery, he became renowned for his autobiographical writings and powerful oratory, offering a living refutation against the slavist argument of the inferior capacity of African Americans. His most famous speech, What to the Slave Is the Fourth of July? , given to the Rochester Ladies' Anti-Slavery Society in 1852, is an acute analysis of how the American values of freedom and liberty were contradicted by the state and treatment of those in slavery.

9

Theodore Roosevelt: The Man in the Arena

"Citizenship in a Republic" is one of Theodore Roosevelt’s most memorable speeches. He delivered it on April 23, 1910, at the Sorbonne in Paris, after leaving the presidency. In his long address, Roosevelt explains his convictions about democracy, civic virtue, and leadership. But there is a passage that stands out: "The Man in the Arena" highlights the value of those who strive and go on despite failure and ongoing challenges, and even those who fail in the end, but not for lack of effort . This passage has been quoted numerous times in American politics, including by Richard Nixon in both his 1968 victory speech and his 1974 resignation address.

10

Ronald Reagan: Tear Down this Wall

More than two decades after Kennedy’s " Ich bin ein Berliner " speech, President Reagan delivered another historic address at the Berlin Wall. Speaking at the Brandenburg Gate in a Berlin much more hostile to the American president’s presence, aides and advisors had recommended a change in the tone of the speech to avoid straining the relationship between the American and Soviet administrations . Reagan retained the passage that had caused concerns, which contained the most iconic phrase. In a direct appeal to the Soviet leader Mikhail Gorbachev, he declared: "Mr. Gorbachev, open this gate! Mr. Gorbachev, tear down this wall!" The speech was not widely covered by the media, and the reactions were lukewarm. Only after the fall of the Berlin Wall in 1989 did the address gain widespread recognition as a symbol of American resolve during the final years of the Cold War.