1

Too slow

Image: Milad Fakurian

If your computer suddenly starts running much slower than usual, this could be a virus infection giveaway, since viruses can cause a computer to perform significantly worse than usual by consuming a lot of resources .

2

Too hot

Image: Artur Solarz

If your computer's fan suddenly becomes unusually loud, this could be a virus warning. If this happens, the computer is being pushed to its limits by some software , possibly a virus, causing the CPU to heat up.

3

Increased random pop-ups

Image: KOBU Agency

Pop-ups are a common nuisance on the internet. However, if you notice a sudden increase in random pop-ups, it could indicate that your computer is infected with a virus. Some pop-up ads contain malware that, if clicked, can install itself on your computer and run without your knowledge. These pop-ups may appear as error messages, or even messages claiming your computer has a virus .

4

Repeated crashes and freezes

Image: Joshua Hoehne

A computer may crash or freeze when running a resource-intensive program or app. However, if it crashes or freezes frequently without any demanding programs running , it could be a sign of a virus infection .

5

Browser homepage changes

Image: Nathana Rebouças

A browser’s homepage should not change unless the user modifies it. At most, it may open a separate tab after an update, but it won’t alter the homepage. If your browser’s homepage unexpectedly switches to a different website , your computer may be infected with a virus .

6

Unknown programs

Image: KOBU Agency

An unknown program or app appearing on a computer could be an indicator of virus presence. A hidden virus may be launching programs that the user did not download .

7

Computer battery draining

Image: Roberto Sorin

As we’ve learned, viruses consume a lot of resources, and a computer’s battery is no exception . When a computer’s battery life quickly drops, this could mean a virus is running in the background and spreading to affect the system.

8

Missing files and corrupted data

Image: Markus Spiske

Missing or corrupted files can also indicate a virus infection on a computer. Heuristic viruses often target files, causing them to disappear or become unreadable . This not only disrupts the workflow but also poses a significant threat to personal and professional information, such as important documents, cherished photos, or critical work files.

9

Unfamiliar files and folders

Image: Cookie the Pom

Computer viruses not only make files disappear but also create files and folders to disguise their presence. Some viruses modify files on a computer by giving them almost identical names, allowing them to blend in with the rest of the documents.

10

Disabled security tools

Image: Ed Hardie

Antivirus programs and security tools are some of our best allies against computer viruses. That’s why, when a virus infects a computer, it often disables security features to make its job easier. Some viruses are specifically designed to disable security tools, giving them access to the computer’s data and private information. If an antivirus program has been disabled, it could be a sign that a virus has shut it down.

11

Unknown emails in the Sent folder

Image: Justin Morgan

Checking the Sent messages folder in one’s Inbox every once in a while is a smart thing to do. Some viruses gain access to a target’s contact list and send emails from their address , spreading malware to other recipients.

12

Unable to access the computer or accounts

Image: Simon Hattinga Verschure

A computer virus may completely block a genuine user’s access . If you realize that you can’t access your online accounts or your entire computer, this can be a sure sign that a virus is running on your computer.

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

Columbus discovered America

Image: Hector John Periquin

Although this isn't strictly about the United States, it does concern our continent. It's often said that Columbus "discovered" the Americas in 1492, but that's not precisely true. He wasn't even the first outsider to arrive! The Vikings, led by Leif Erikson, reached North America around the year 1000 AD, almost 500 years before Columbus. And, of course, the continent was already inhabited long before any European explorers arrived.

2

George Washington had wooden teeth

Image: Priscilla Gyamfi

One of the most famous historical myths is that George Washington, the first US president, had wooden teeth. While it's true that he struggled with dental problems and used several prosthetic devices made from various materials, none of his teeth were actually made of wood.

3

The US Declaration of Independence was signed on July 4, 1776

Image: Glen Carrie

Every 4th of July, the country turns into a party. And it's no wonder, since we're honoring Independence Day! Perhaps because of the date of this holiday, many people believe that the US Declaration of Independence was actually signed on July 4, 1776. In reality, the key event on that day was the Continental Congress voting to adopt the Declaration of Independence. Most delegates actually signed the document later, on August 2, 1776, in Philadelphia.

4

America became fully independent in 1776

Image: The New York Public Library

On July 4, 1776, the American colonies declared their independence from Great Britain by adopting the Declaration of Independence. However, the Revolutionary War continued for several more years. It wasn't until the war ended in 1783, with the signing of the Treaty of Paris, that the United States' independence was officially recognized.

5

Cowboys wore Stetson hats

Image: Brice Cooper

Although Stetson hats are now inseparable from the cowboy image, the reality of the 19th century was pretty different. People in the Wild West sported a variety of styles: while some did wear wide-brimmed hats similar to Stetsons, these were not the most common, and many other types were also popular.

6

Paul Revere rode alone

Image: Pixabay

Paul Revere's name became a symbol of American courage and determination. His midnight ride on April 18, 1775, was undoubtedly heroic, but some details have been distorted over time. While many think he shouted "The British are coming!", historians suggest he likely said something closer to "The regulars are coming", given the dates. And contrary to popular belief, Revere didn't ride alone; he was part of a group of riders working together to warn the colonial militia.

7

George Washington chopped down a cherry tree

Image: Jeffrey Clayton

The story of George Washington chopping down a cherry tree is one of the most famous tales in American history. However, it's actually a myth, created by one of Washington's early biographers to highlight one of his defining characteristics: honesty. Although there is no reliable historical evidence to support this famous anecdote, there is plenty of proof of the courage and honesty of the Father of His Country.

8

Al Capone was jailed for his violent crimes

Image: Ashim D’Silva

Al Capone was one of the most infamous gangsters in history. Although his life was filled with criminal activity, it wasn't his violent acts that put him in jail, as there wasn't enough evidence to convict him. Instead, authorities used tax evasion charges, and he was finally imprisoned for that reason in 1931.

9

Prohibition made drinking illegal everywhere

Image: Drew Beamer

Many people assume that drinking alcohol was completely illegal during Prohibition. In reality, the 18th Amendment and the Volstead Act (1920–1933) banned the manufacture, sale, and transportation of alcohol, but not the act of drinking itself!

10

The Founding Fathers as a unified group

Image: J. Amill Santiago

Many believe the Founding Fathers worked as a unified group, sharing a single vision without disagreement. But history tends to be a little more complex. While they collaborated and worked hard to establish the United States, they held diverse ideas and visions for the nation, and some even became rivals. Yet, despite their differences, they successfully laid the foundations for the first large-scale modern republic.