Behind the Façade: 40 Surprising Facts About the Hidden Secrets of Famous Landmarks

Mount Rushmore, located in South Dakota, is a national monument that honors four American presidents. Behind the monument is a room that was intended to house important documents and information about the carving of the presidents' faces. However, construction of the room was halted when the government ordered the sculptor to focus on the faces instead. The room now contains 16 porcelain and enamel tablets describing the project and a brief history of the United States. The tablets are kept in a teakwood box and sealed inside a titanium vault, located behind Lincoln's hairline.

Angkor Wat, located in Cambodia, is the largest religious structure in the world. Built in the early 12th century, it was originally a Hindu temple before being converted to a Buddhist temple. The temple complex is massive, spanning over 80 times the size of St. Peter's Basilica in Vatican City and at least 3.5 times the size of the entire Vatican City. Unlike the Egyptian pyramids, which were built with stone quarried from only 0.5 km away, Angkor Wat was constructed using stone quarried from over 35 km away, making it one of the most impressive engineering feats in history.

Peter's Basilica in Vatican City, one of the most important Catholic churches in the world, was funded by selling indulgences—letters excusing you from sin. Rich people even bought these in advance for sins they planned on committing. During the demolition of Old St. Peter's Basilica in the Vatican in the 17th century, over 100 papal tombs were destroyed.

When the Hoover Dam was being drafted, engineers calculated that it would take 125 years for the concrete to cool if done in a single pour. Instead, they poured it in sectioned blocks, some as big as 50 square feet and 5 feet high. This way, the physical dam itself will survive up to 10,000 years and be one of the last remaining visible and recognizable monuments of humans on the planet. Also, the first death occurred on December 20, 1922, during its construction. Exactly 13 years later, on December 20th, 1935, the last death occurred, and the two men were father and son, respectively.

Petra in Jordan had a more efficient and advanced water system than ancient Rome, with a sophisticated water management system that allowed its 40,000 inhabitants to survive in the harsh desert environment. Scientists have discovered a hidden monument in the center of Petra using high-resolution satellite images, drone photos, and ground surveys, and they estimate there are still many undiscovered tombs and ruins buried beneath the ground. Despite extensive archaeological excavations and research, only about 15% of the ancient city has been fully explored and documented.

There is a "secret" entrance to the Louvre that allows you to bypass the ridiculous line at the public entrance. The Porte des Lions entrance is the best entrance into the Louvre. From this entrance, you can buy your tickets, enter the museum, and have the shortest route to the Italian Renaissance painting section. This door always has the shortest line. Also, if you wanted to see every piece of art in The Louvre in one visit, it would take you over a month, assuming you were there 24/7 and took no breaks or sleep.

"Kremlin" means "fortress inside a city," and there are multiple kremlins in Russia. "The Kremlin," which is popularly known, refers to the Moscow Kremlin, which includes five palaces, four cathedrals, and the defensive walls and towers. Supposedly, the whole of Moscow has a secret underground metro system that parallels the public Moscow metro, which connects the Kremlin to the FSB headquarters as well as other locations of national importance. Additionally, some of the Soviet Union's honored dead were buried inside the Kremlin wall.

The Parthenon in Athens has stood largely intact for more than 2000 years, but the ruins we see today are the result of a massive explosion in 1687, not natural forces or the passage of time. During a war between Venice and the Turks, the Venetians hit the building with a mortar round, causing the explosion. The Turks were using the building to store gunpowder, and it is said they didn't expect such a historic monument to be targeted. Tragically, the blast killed 300 people. Originally built as a temple for the goddess Athena, the Parthenon has served as a church and mosque throughout its history.

The Tower of Hercules, located in A Coruña, Galicia, Spain, is the oldest extant lighthouse in the world and is still in use today. Built between the 1st and 2nd centuries A.D., it was modeled after the Lighthouse of Alexandria.

Edinburgh Castle in Scotland was built on top of a volcano and is so old that its founding was already shrouded in myth and legend by the time of its first definite mention in literature. The infamous "Red Wedding" scene from "A Storm of Swords" by G.R.R. Martin was inspired by real-life events that occurred at Edinburgh Castle in 15th century Scotland, known as "The Black Dinner". Additionally, the castle has a secret underground tunnel leading to nearby Holyrood Palace, which was rediscovered during a renovation project in the 1990s and is now open to the public for guided tours.