French President Emmanuel Macron vowed to rebuild Notre Dame Cathedral after a massive fire tore through the centuries-old church on Monday.

Restoring the iconic cathedral would likely be complicated, lengthy and expensive, experts said.

But they also appeared optimistic that such a rebirth is possible.

Jonathan Foyle, an architectural historian and author, said a critical part of the restoration process will be to assess how damaged Notre Dame’s massive stone vaults were by the blaze. Extreme temperatures can cause calcination — a process that turns stone into powder, he said.

Then, there’s the possible damage caused by firefighters trying to extinguish the blaze: Dumping cold water on red hot stone can cause it to shatter and crack, Foyle said.

“It’s gone through a very complex trauma,” he said. “You’re going to need months to figure out whether it is safe enough to stay standing.”

Foyle said there are French architects trained in medieval building techniques that would be up to the task of restoring this “pioneering giant of Gothic cathedrals.”

“This building has been through the French Revolution, the Huguenots and two world wars,” he said. “I have no doubt it will rise again.”

If the stones were badly "baked" during the blaze that may mean the vaulted roof and surrounding walls have to be dismantled, according to Paul Binski a professor of the history of medieval art at the U.K.'s Cambridge University.

"Stone doesn't burn but it bakes, so my estimation is that they will have to take the entire vaulting system of the church down because it simply will not be safe," said Binski, who specializes in the art and architecture of Western Europe in the Gothic period. "That may involve taking the upper walls down, to a certain degree, depending on the extent of the damage."

The rebuilding process could take two decades of painstaking work and restructuring, said Emily Guerry, a professor of medieval European history at Britain's University of Kent.

“The cost will be unimaginably high, but it’s worth every penny,” Guerry said, adding that the “delicate” work required to restore the cathedral to its original Gothic style will be France’s largest and most important renovation project for the next 20 years.

Annabelle Radcliffe-Trenner, a principal at Historic Building Architects in New Jersey, called the fire “devastating” but also believed that the cathedral could be resurrected.

She pointed to massive fires at St. Bernard’s Episcopal Church, a Gothic-style structure in New Jersey that she was involved in rebuilding, and Windsor Castle, the iconic royal residence in Berkshire, England, that burned in 1992.

The castle’s chapel was badly damaged, she said, “but it’s been fully restored — which you could tell from the big wedding last year. Restoration can be done; it’s just painstaking work.”

She said experts would "go in slowly, peeling back the damage safely and getting people to evaluate” what was lost and what can be saved.

“The key is getting in very quickly to stabilize things like stained glass,” she said.

Any actual rebuilding will take “years and years and years,” Radcliffe-Trenner said.

Foyle estimated that it will cost tens of millions of dollars and require an army of stone masons, glaziers, plumbers and carpenters.

Still, such a massive project could signal a “rebirth,” he said.

“In a way, projects like Windsor Castle — they look disastrous, and they are, but they give life to traditional trades,” he said. “Sometimes they can have a silver lining.”