By CCN.com: Millions watched with tears in their eyes as Notre Dame was ravaged by fire on Monday night. The cathedral’s iconic spire was engulfed in flames before collapsing into ash, and 100 meters of wooden roof work was destroyed.

France’s president Emmanuel Macron said the “worst had been avoided,” but attention now turns to the rebuilding effort. In front of the Paris cathedral, he vowed:

“We’ll rebuild Notre-Dame together. I am solemnly telling you tonight: this cathedral will be rebuilt by all of us together. We will rebuild Notre Dame because that is what the French expect, because that is what our history deserves, because it is our destiny.”

Notre-Dame is aflame. Great emotion for the whole nation. Our thoughts go out to all Catholics and to the French people. Like all of my fellow citizens, I am sad to see this part of us burn tonight. https://t.co/27CrJgJkJb — Emmanuel Macron (@EmmanuelMacron) April 15, 2019

How Much Will it Cost to Rebuild Notre Dame?

Macron’s promise won’t come cheap. Early estimates put the cost of rebuilding in the multi-billion euros.

To understand the staggering costs involved, we need to assess the damage. Here’s what we know so far:

Roof – two-thirds of the Notre Dame roof has been destroyed (including a 100m section).

– two-thirds of the Notre Dame roof has been destroyed (including a 100m section). Spire – the spire is completely destroyed.

the spire is completely destroyed. Stained glass windows – A 62-foot window appears to have been severely damaged.

– A 62-foot window appears to have been severely damaged. Organ – the 800-pipe organ is one of the largest in the world. We don’t yet know the extent of the damage.

– the 800-pipe organ is one of the largest in the world. We don’t yet know the extent of the damage. Stone-work – Architects say the stonework is likely to be weakened by the fire. Extreme heat can turn stone into dust through a process called calcination.

– Architects say the stonework is likely to be weakened by the fire. Extreme heat can turn stone into dust through a process called calcination. Firefighting damage – Pouring cold water on hot stone causes it to crack and weaken.

– Pouring cold water on hot stone causes it to crack and weaken. Artwork and priceless relics – Firefighters were seen ushering artwork out of the cathedral. A relic of Christ’s crown of thorns is said to be safe, but the cost of repairing damaged artwork could run into the millions.

Firefighters will continue working over the coming week to contain the damage. Only then we will we know the true costs of rebuilding.

Call for donations to help rebuild Our Lady of Paris, Notre-Dame cathedral, after the brutal fire that has partly destroyed it. 🙏

The Fondation du patrimoine is a private organization dedicated to saving french cultural and natural heritage.

➡https://t.co/QAB3kFhsK0 pic.twitter.com/0fv4Nc3fl1 — Fondation du patrimoine (@fond_patrimoine) April 15, 2019

Billion Euro Rebuilding Project

Even before the fire, Notre Dame was wildly expensive to maintain. More than €4 million ($4.5 million) was spent every year on basic renovations. Experts say it would cost €150 million just to conduct essential structural work. And that’s before the fire hit.

We should also take into account the loss of income from tourists. Although Notre Dame is free to enter, it costs €8.50 to visit the tower and €6 to go into the crypt. With 13 million visitors every year, the cathedral stands to lose millions in tourist revenue.

"In the wake of this national tragedy, the Arnault family and the LVMH Group pledge their support for #NotreDame. They will donate a total of 200 million euros to the fund for reconstruction of this architectural work, which is an integral part of the history of France." pic.twitter.com/utvJT8xJht — LVMH (@LVMH) April 16, 2019

French Billionaires Swoop in to Pledge Money

Two of France’s richest men have already pledged a combined €300 million to rebuild the Paris cathedral. François-Henri Pinault (CEO of the company that controls Gucci and Yves Saint Laurent) has pledged €100 million. He said:

“My father and I have decided to release from the funds of Artemis a sum of €100m to participate in the effort that will be necessary for the complete reconstruction of Notre Dame.”

Bernard Arnault (head of LVMH) gifted a further €200 million for restoration:

“The Arnault family and the LVMH group would like to show their solidarity at this time of national tragedy, and are joining up to help rebuild this extraordinary cathedral, which is a symbol of France, of its heritage and of French unity.”

French charity Fondation du Patrimoine has opened up a call for donations. And the French Heritage Society, based in the US, has launched a restoration fund.

As the embers burn in Paris, the staggering cost of rebuilding will slowly become clear.