The iconic Washington Monument is celebrating its birthday today. Learn how it took 40 years to complete the project, and the surprising connections it has to the Pope, Abraham Lincoln, and the Constitution.

The Washington Monument officially was dedicated on February 21, 1885. In a speech written for that event by Robert Winthrop, who attended the groundbreaking ceremony in 1845, there was one memorable line: “An earthquake may shake its foundations … but the character which it commemorates and illustrates is secure.”

That’s not the only interesting fact or coincidence about the iconic monument. Here are 10 more fascinating facts about this American symbol.

1. James Madison had an early role in getting the monument project started. In 1833, the Washington National Monument Society, a private organization, was among early groups promoting the idea for the tribute to the first President. Madison along with Supreme Court Chief Justice John Marshall started the society.

2. The first monument design featured a rotunda and a Roman-like George Washington. The initial winning bid came from architect Robert Mills, whose designed a flat-topped obelisk with a statue of Washington in a chariot, along with statues of 30 Founding Fathers. The current obelisk design was proposed in 1876.

3. The Masons and the Pope were involved with the monument. Yes, the Free Masons were involved in the cornerstone ceremony and they used Washington’s Masonic symbols in the ceremony. At the 1848 ceremony were 20,000 people, and a container that held copies of the Constitution, the Declaration of Independence and other objects was buried in the cornerstone.

4. Abraham Lincoln was at the 1848 cornerstone ceremony. The guest list included three James Buchanan, Lincoln, Andrew Johnson, Dolley Madison and Alexander Hamilton’s widow, Betsey Hamilton, and of course, the then-current President, James K. Polk.

5. So how does the Pope fit into all of this? The Society asked for people to donate ceremonial stones as part of the construction process. Pope Pius IX donated a memorial stone of marble, which infuriated the anti-Catholic Know Nothing Party. The Know-Nothings got their revenge by rigging the leadership election for the Washington National Monument Society. Congress cut off monument funding for 5 years until the Know Nothings left the group.

6. Nothing happened to the monument for a 22-year period. After the Know-Nothing takeover in the 1850s, the monument became stalled to the point that it was used as a slaughter yard and cattle pen during the Civil War. Congress took over the project in 1876.

7. It took the U.S. Army Corps of Engineers to get the job done. The Engineers worked with Lt. Col. Thomas Lincoln Casey to modify the original ornate plans. The monument’s stripped-down, lean look was part of a cost-cutting effort. On December 6, 1884, an aluminum cap used as a lightning-protection device was placed on top. In February 1885, the dedication ceremony took place.

8. The Monument was the world’s tallest building when it was dedicated. The Washington Monument as dedicated stood at 555 feet 5 inches tall. The Cologne Cathedral had been the world’s tallest man-made structure. The Eiffel Tower soon surpassed the Monument.

9. The Monument is an engineering marvel. The Monument’s marble blocks are held together by just gravity and friction, and no mortar was used in the process.

10. The Washington Monument: Movie star. Nothing says “location shot” in a film like the Washington Monument, especially when the icon is under attack from aliens and terrorists, or used as a backdrop in a thriller or mystery. But maybe the most memorable appearance, in a real-life moment, occurred in August 1963, when Martin Luther King Jr. spoke on the mall in Washington, with the Lincoln Memorial stage facing the Monument.