The Gateway Arch, the 630-foot-tall monument located on the west bank of the Mississippi River in St. Louis, Missouri, is famous for being the world's tallest arch. But few people know about the secret hidden at its peak.

In 1965, before the final piece of the stainless steel arch was put in place, a time capsule containing the signatures of 762,000 St. Louis students and residents was welded into the keystone. Just one more fun fact added to the mystique of this midwestern icon!

Image: Roger Miesfeld

Have you ever wondered where Hollywood's golden age films are preserved? Well, as it happens, they are not in the basement of some Tinseltown studio but more than 650 feet below the surface in a facility in Hutchinson, Kansas. Established in 1959, Underground Vaults & Storage specializes in storing a wide range of valuables, including paper documents and client records.

In addition, this site is a precious resource for the entertainment industry. Underground Vaults & Storage preserves—under optimal temperature and humidity conditions—film copies of classic cartoons, television programs like Friends, game shows, soap operas, and even the original reels of cinematic masterpieces like The Wizard of Oz and Gone with the Wind.

Image: Denise Jans

Who says a building has to look traditional to be iconic? Why settle for an ordinary office building when you can work inside a basket? That's what the executives of the Longaberger Company, an American manufacturer and distributor of handcrafted maple wood baskets, thought when they relocated to Newark, Ohio, in 1997.

Their headquarters was designed as a seven-story building, a perfect replica of the company's top-selling product, the Medium Market Basket. The massive handles are attached to the structure with copper and wooden rivets, and the gold-leaf-plated tags each weigh 725 pounds. Though the building was a novelty, the company eventually abandoned it, and it is now listed for sale.

Image: Photo shot by Derek Jensen (Tysto, Public domain, via Wikimedia Commons

Popping the question on top of the Empire State Building has become a cherished tradition in the United States. Thousands of couples travel from all over the country to get engaged at one of New York City's most iconic buildings. But did you know that you can also celebrate a wedding there?

Every February 14, a few lucky couples are granted the unique opportunity to exchange wedding vows at the building's 86th Floor Observatory. Since 1994, hundreds of couples have said "I do" at this breathtaking location, celebrating Valentine's Day at America's most romantic landmark.

Image: William Wachter

Creativity, ingenuity, and perseverance can achieve extraordinary feats. Such is the case with Coral Castle, a massive limestone structure built by self-taught engineer Edward Leedskalnin in the early 20th century.

Located just north of Homestead, Florida, sits this construction built with stones larger than those at Stonehenge. Leedskalnin, who invested more than 28 years in this project, claimed that he raised it single-handedly using reverse magnetism and supernatural abilities. The truth is he probably used pulleys and other tools, but that doesn’t make it any less of a unique and original building that is a fascinating tourist attraction to this day.

Image: Michelle_Raponi

Walt Disney was a visionary, and thanks to his infinite imagination today we have the most endearing characters and the best amusement parks in the world. But did you know that Disney originally envisioned his famous EPCOT Center as the blueprint for a larger utopian society?

EPCOT stands for Experimental Prototype Community of Tomorrow. Had Disney’s dream come to fruition, 20,000 people could have lived in a real, futuristic city complete with residential areas, shopping malls, factories, recreational parks, and a state-of-the-art multimodal road system to connect it all. Unfortunately, after his death in 1966, the company felt his original vision was a bit impractical. Instead, they created a theme park that captures the spirit of its creator, a permanent celebration of human achievement, from culture to technological innovation.

Image: Paul Moody

The CIA is a mysterious organization, so it's no wonder that there is a sculpture hiding secrets sitting right in the courtyard of the George Bush Center for Intelligence in Langley, Virginia.

Named "Kryptos," this large copper sculpture was installed in 1990 and holds a series of four encrypted messages. Only three of these codes have been cracked, while the fourth remains one of the most famous unsolved cryptograms in the world.

Image: Pixabay

It seems that the 1920s was a time of inventiveness, innovation, and originality in architecture. During this decade, the United States built the most impressive skyscrapers and, as we've explored, even a massive limestone castle. But a house made of paper? It seems almost impossible, doesn’t it?

Well, we are about to prove you wrong. In 1924, a mechanical engineer called Elis Fritiof Stenman built a summer cottage made almost entirely out of pasted, coated, or rolled-up newspapers. The only exceptions were the framework, floorboards, and shingles. The house is located in Rockport, Massachusetts, and, believe it or not, is still standing and can be visited.

Image: Daderot, Public domain, via Wikimedia Commons

The Chrysler Building on the East Side of Manhattan in New York City was once the world’s tallest building, holding the title for 11 months. But did you know that it almost didn't make it? Industrial pioneer Walter Chrysler, who commissioned the project, wanted his building to be taller than the Eiffel Tower. Originally designed to be 925 feet tall, the imminent construction of other taller skyscrapers forced architect William Van Alen to revise his plans.

This competition for the title of the world’s tallest building became known as the "Race into the Sky." To beat his opponents, Van Alen ordered a 125-foot spire to be built in secret. It would only be attached to the roof after the rival buildings were finalized. When it was finished in May 1930, the Chrysler Building reached 1,046 feet, making it the tallest man-made structure in the world at the time. Unfortunately, less than a year later, the Empire State Building would claim that honor.

Image: roberto_bellasio

Did you know the world's only undersea research laboratory is located in the United States? Sixty-six feet below the surface of the ocean off the coast of Florida lies Aquarius Reef Base, an underwater lab where researchers work for up to ten days at a time.

Aquarius is dedicated to the study and preservation of coral reefs, fish, and aquatic plants. The facility is currently operated by Florida International University and contains sophisticated state-of-the-art lab equipment.

Image: NEOM

A bridge that tells time? We are not kidding! When it’s not being used by pedestrians and cyclists to cross the Sacramento River in Redding, California, the Sundial Bridge at Turtle Bay serves as a giant timepiece.

The bridge's 217-foot support tower points north, and its shadow can be used to calculate the time. Designed by renowned Spanish architect Santiago Calatrava, it was completed in 2004. So now you know, if your watch breaks or your cell phone dies on your way to Turtle Bay Exploration Park, you don't have to worry, the Sundial Bridge will always tell you the time of day!

Image: Leo_Visions

Few people know that a network of subway cars runs beneath Washington’s labyrinthine Congressional headquarters. The first Capitol Subway System opened on March 7, 1909, and has been transporting politicians seeking shelter from the weather—and curious onlookers—for more than a century.

The rails stretch for nearly a mile, connecting the United States Capitol to several congressional office buildings. While the public can ride the trains, the subway is restricted to congressional members and staff during votes.

Image: Harrison Haines