Paris's Notre Dame Cathedral Before the Fire: An Unforgettable History in Photos (Video)

A massive fire broke out at the historic Notre Dame cathedral in Paris on Monday, causing part of the iconic building to collapse. Though the cause of the fire remains unclear, early reports indicate it may have begun at a construction site on the property.

Tourists and locals could only stand by as the cathedral's spire went up in flames and later collapsed. According to NBC, the spire contained artifacts sacred to the Catholic faith, including a relic believed to be from Jesus Christ's crown of thorns. Other relics from Saint Genevieve and Saint Denis may also be destroyed.

"Everything is burning, nothing will remain from the frame," Notre Dame spokesman Andre Finot told reporters.

Beyond housing important holy items, the cathedral has a deep and rich history. Here's what you should know about the Notre Dame cathedral.

Notre Dame cathedral is more than 850 years old.

Notre Dame, The New York Times explained, was commissioned in 1163, during the reign of King Louis VII. The building was completed in 1345. According to The Guardian, King Louis VII wanted the building to be a "symbol of Paris's political, economic, intellectual, and cultural power at home and abroad." The first stone was laid in 1163 in the presence of Pope Alexander III.

This isn’t the first time Notre Dame has been damaged.

As The Times added, the building fell into disrepair during the French Revolution. Its decrepit state was even documented in Victor Hugo's 1831 novel, "Notre-Dame of Paris," otherwise known as "The Hunchback of Notre Dame."

But, in 1844, architects Jean-Baptiste-Antoine Lassus and Eugène-Emmanuel Viollet-le-Duc worked to bring the cathedral back to its former glory and revamped both the building's spire and flying buttresses.

Notre Dame hosted many major moments in history.

According to The Guardian, in 1431 Henry VI, the then-king of England, was crowned king of France, and in 1537 James V, the then-king of Scotland, married Madeleine of France. And, in 1909, Joan of Arc was declared innocent and was beatified inside the Notre Dame cathedral by Pope Pius X.

The cathedral also houses incredibly rare and important artifacts.

Inside the Notre Dame Cathedral is a 17th-century organ that still remains functional today (though its fate post-fire is not yet known). Beyond the organ, drawings, plans, and engravings showing "the old and hidden mysteries of several of the church developments and how the city of Paris came into being" sit inside, according to the cathedral website.

And, according to CBS, the cathedral also houses the woven crown of thorns believed to have been placed on Jesus Christ's head during his crucifixion. According to the cathedral's website, the crown now consists of a ring of rushes, bound by gold threads and enclosed in a gold and glass frame. The thorns of the crown, the site noted, have been plucked off and given as gifts to donors and important religious figures throughout history.

The cathedral also houses a piece of the wooden cross along with a nail believed to have been used to crucify Jesus. Other historically significant items include stained-glass windows, statues, gargoyles, and more.

"It's been 800 years that the Cathedral watches over Paris," French historian Camille Pascal told Canada's BFM. "Happy and unfortunate events for centuries have been marked by the bells of Notre Dame."

Now, all we can do is sit and wait to see what makes it out of the flames and hope the city of Paris is able to rebuild.