The fire that consumed the iconic 300-foot spire burned through a large amount of wood on the inside and outside of the building, but some treasures were saved by the more than 500 firefighters who battled the blaze for 15 hours, at one point risking their lives by staying inside to build a wall of water between the fire and the bell towers. Fire officials revealed that the 850-year-old cathedral was within 15 to 30 minutes from being entirely consumed. As it was, a large amount of the wooden frames inside were charred.

The famous organ, which has 8,000 pipes, is intact. It dates to the 1730s. The cathedral's three very large rose windows are still there, as was what is thought to have been a piece of wood from the Crown of Thorns that the Bible says Jesus wore on the Cross. The cathedral was home to many more famous and irreplaceable works of art, however, and officials are already undertaking a damage assessment. Many other smaller stained glass windows already number among the artistic and architectural casualties.

Donations exceeding 800 million euros have poured in from around the world and will no doubt come in handy in what is certain to be an expensive, long restoration effort. French President Emmanuelle Macron announced a timeline of five years for such a feat; experts warned that it could take decades.

One thing that could help is a set of high-tech laser scans taken by American art historian and Vassar professor Andrew Tallon from more than 50 spots in and around the cathedral in 2010. In all, he and Columbia's Paul Blaer collected 1 billion points of data in the five days of scanning. He also took high-resolution panoramic photos in order to create a mapping opportunity of photo to scan. A close look at the scans revealed the kind of cost-cutting that was thought to have taken place during the 1844 restoration inspired by the publication of Victor Hugo's famous book Notre-Dame de Paris, known in English as The Hunchback of Notre Dame.

The fire is thought to have started at 6.30 p.m. Paris time. Exactly 24 hours later, more than 100 cathedrals all across the country tolled their bells in unison.

As for the cause of the fire, officials have talked do a few dozen people already and have ruled out arson and a terrorist attack. No one was killed in the blaze. Injured were one firefighter and two police officers.

The centuries-old cathedral was built at the behest of Bishop of Paris Maurice de Sully, on the site of what is believed to have been a pagan temple and then a Romanesque church known as the Basilica of Saint étienne. Construction began in 1163, with the laying of the foundation stone by Pope Alexander III and completed nearly a century later, in 1260.