On March 31, 1889, the Eiffel Tower opened to the public. Below are some things you might not know about the beloved monument.

1. The tower was built as an entrance arch for the 1889 World's Fair.

To mark the 100th anniversary of the French Revolution, Paris hosted the 1889 World’s Fair (Exposition Universelle). Hoping to be considered for the high-profile project, artists from around the nation sent in plans for a structure to mark the entrance to the fair on the Champ-de-Mars, a public greenspace in the center of Paris.

2. It was designed and built by the firm Eiffel et Compagnie.

The commission was given to the consulting and construction firm owned by Gustave Eiffel, a bridge builder, architect, and metals expert. Eiffel also worked in the early 1880s on the Garabit Viaduct, a bridge in the Massif Central region that was, at the time, the highest bridge in the world. Prior to landing the World's Fair project, he also helped design the Statue of Liberty.

3. Gustave Eiffel rejected the initial design.

The tower's main designer was one of Eiffel’s employees, senior engineer Maurice Koechlin. Engineer Emile Nouguier and the head of the company’s architectural department, Stephen Sauvestre, were also consulted. After viewing Koechlin's initial sketches—which Eiffel felt were too minimalist—the architect instructed Koechlin to include more details and flourishes in his redesign. Eiffel approved the final design in 1884.

4. The project required lots of metal (and lots of manpower).

Three hundred steel workers spent two years, two months and five days, from 1887 to 1889, constructing the Tower. They used more than 18,000 individual metallic parts, 2.5 million rivets, and 40 tons of paint.

5. Its original height was 985 feet.

Upon its completion in March 1889, the Tower measured 300 meters (985 feet) high. Surprisingly, this measurement isn't static: Cold weather can shrink the Tower by up to six inches.

6. It was the tallest structure in the world until 1930.

For 41 years, the Eiffel Tower stood higher than any building or structure in the world—until it was surpassed by the Chrysler Building in New York, which topped out at 1046 feet. Just a year later the Empire State Building became the tallest in the world at 1454 feet with the spire. In 1957 an antenna was added that increased the Tower’s height by 67 feet, making it 6 feet taller than the Chrysler Building.

7. A 300-member committee protested the tower.

Led by author Guy de Maupassant, Alexandre Dumas, Jr., and hundreds of other artists and intellectuals, a petition opposing the project was signed and sent to the Parisian government. They called the Tower “useless and monstrous,” but their protests fell on deaf ears.

8. The tower was an immediate hit.

Despite the petition, the 1889 World’s Fair was deemed a great success, thanks largely to the Tower's imposing presence. Nearly 2 million people visited the Eiffel Tower during the Fair and spent $1.4 million on tickets, making the 1889 Fair one of the few to actually turn a profit.

9. It was only supposed to stand for 20 years.

The Eiffel Tower was never intended to stand over the Champ-de-Mars permanently, and was scheduled to be dismantled in 1909—that is, until someone realized that its apex was the perfect place for a telegraphy antenna. During the First World War, at the Battle of Marnes in 1914, the wireless telegraph transmitter helped jam German communications.

10. It moves!

Eiffel, a renowned expert on aerodynamics, published “The Resistance of the Air” in 1913. He and his team designed the Tower to withstand even the strongest winds, and never sway more than 4.5 inches.

11. There are three levels.

The 7 million people who visit the Eiffel Tower every year can now travel to three different sections of the Tower at three different heights. The first level is 189 feet high and includes an observation area, a reception room named after Gustave Eiffel, souvenir shops, an art show, a restaurant (58 Tour Eiffel) and a transparent floor. The second floor, at 379 feet, includes another observation area and Le Jules Verne restaurant. The top level offers amazing panoramic views at 905 feet high and a champagne bar, where you can grab a glass of white or rosé (just expect to pay up to $25 per glass).

12. Some weird events have taken place there.

The tower has drawn its share of daredevils (Pierre Labric, the future mayor of Montmartre, was arrested for cycling down its stairs in 1923) and overly-enthusiastic admirers. In 2007, a woman with an "objectum sexual" married the tower and changed her name to Erika La Tour Eiffel.

13. The tower gets a fresh paint of coat every seven years.

About 60 tons of paint are needed to freshen the monument, which is owned by the City of Paris and operated by a public utility called the Société d'Exploitation de la Tour Eiffel (SETE). More than 500 people work for the SETE, as tour guides, security, in the post office, and in the Tower’s restaurants, shops, and boutiques.

14. The tower was closed during the German occupation.

French resistance fighters cut the cables for the Eiffel Tower’s lifts so Nazi officers and soldiers had to climb the stairs, and the monument was closed to the public during the occupation from 1940 to 1944. Hitler actually ordered the military governor of Paris, Dietrich von Choltitz, to destroy the Tower, along with the rest of the city; fortunately, his order wasn’t carried out.

15. The iconic structure is beloved by filmmakers.

James Bond chased an assassin through the Tower in A View to a Kill. A murder-mystery called The Man on the Eiffel Tower was released in 1949 and starred future Penguin Burgess Meredith. A scene from The Lavender Hill Mob, which featured future Oscar winners Alec Guinness and Audrey Hepburn, was filmed there. Hundreds of other films have used the Tower as a prop, or a backdrop.