After the devastating fire at Notre Dame Cathedral on April 15, French President Emmanuel Macron vowed that the iconic landmark would be rebuilt by 2024, in time for the Summer Olympics in Paris.

Even with over a billion dollars already pledged for rebuilding, many experts have chimed in with a "not so fast" urging in an open letter to the president published on Sunday by French newspaper Le Figaro.

Some 1,169 academics and curators signed the long letter, including dozens of French curators; Philippe de Montebello, the former director of the Metropolitan Museum of Art; Xavier F. Salomon, the chief curator of the Frick Collection; and many others.

“Let’s take the time to diagnose,” the letter reads. “... and then, yes, set an ambitious deadline for an exemplary restoration not only for the present but also for generations to come.”

Notre Dame's wooden spire, roof and other architectural elements, some dating to the 12th and 13th century, were destroyed or damaged. The attic, nicknamed “The Forest,” included 1,300 timber frames, each coming from a unique oak tree, which likely fueled the inferno. 

An international design competition is underway for a new spire and cathedral topper.

The cause of the fire is still under investigation.