Jean-Charles Forgeret poses with archives documents related to Notre Dame cathedral in Charenton le Pont, outside Paris, Thursday, April 18, 2019. The reconstruction of Paris' Notre Dame Cathedral will rely on part on extensive plans drawn up in the 19th century for its last big renovation. Forgeret noted that the last restoration took 20 years, and cast doubt on the French president's 5-year deadline on fixing Notre Dame this time. (AP Photo/Nicolas Garriga)

CHARENTON-LE-PONT, France (AP) — Eugene Viollet-le-Duc is still the man to go to when it comes to restoring Notre Dame, even though he died nearly 140 years ago.

As a young architect in Paris, Viollet-le-Duc made it his life's work to preserve the iconic cathedrals, monasteries and palaces that were damaged during the French Revolution and fell into further disrepair amid an early 19th century economic slump.

His more than 20 years of work on Notre Dame, already prized for its vision and detail, may be put to its greatest use yet. As attention turns to rebuilding the Gothic cathedral significantly damaged by a fire, Viollet-le-Duc's incomparable notes and drawings will give contemporary architects a guidebook to how he approached the job during the mid-19th century.

Jean-Charles Forgeret, an expert on Viollet-le-Duc at the MAP historical monument archives, where the architect's many drawings, notes and blueprints are kept, knows busy times are upon him. Viollet-le-Duc was a relentless worker with a knack for details and the habit of studiously holding onto what he produced. The renovation he undertook at Notre Dame lasted from 1845 until 1865, Forgeret said.

"He left us a very substantial documentation. We have the letters and the work diary where he was writing day after day everything that was happening on the building site," Forgeret told the Associated Press in an interview.

Huge maps with blueprints and watercolor drawings of architectural details spill out of drawers in the archives. One map is a color-coded key of each stone set in the renovation work Viollet-le-Duc oversaw, showing the location and type.

Viollet-le-Duc also designed the iconic spire that so dramatically collapsed in a ball of fire on Monday.

Contemporary restorers will have more than Viollet-le-Duc's drawings to consult since numerous studies of Notre Dame have been done in the years.

Even as construction crews work to shore up the weakened building, there is speculation of which version of the Notre Dame spire will be the model for the rebuilding. Viollet-le-Duc has sometimes been derided for being too interventionist in his restorations; the pointy spire certainly was his alone.

"The spire that he built was a spire of the 19th century, let's be clear," said Forgeret. "It's a creation from the 19th century, but inspired by everything he knew, by all his science and knowledge of the Middle Ages."

French President Emmanuel Macron has set a goal of having Notre Dame rebuilt within five years, which would be in time for when Paris hosts the 2024 Summer Olympics. Viollet-le-Duc would have considered that an impressive feat, archivist Forgeret said.

"We are talking about 20 years in the 19th century for the cathedral to be completely restored. Five years seems to me very, very little," he said.

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Read and watch all AP coverage of the Notre Dame fire at https://apnews.com/NotreDameCathedral

Jean-Charles Forgeret poses with archives documents related to Notre Dame cathedral in Charenton le Pont, outside Paris, Thursday, April 18, 2019. The reconstruction of Paris' Notre Dame Cathedral will rely on part on extensive plans drawn up in the 19th century for its last big renovation. Forgeret noted that the last restoration took 20 years, and cast doubt on the French president's 5-year deadline on fixing Notre Dame this time. (AP Photo/Nicolas Garriga)
An image made available by Gigarama.ru on Wednesday April 17, 2019 shows an aerial shot of the fire damage to Notre Dame cathedral in Paris on Tuesday April 16. Nearly $1 billion has already poured in from ordinary worshippers and high-powered magnates around the world to restore Notre Dame Cathedral in Paris after it was damaged in a massive fire on Monday. (Gigarama.ru via AP)
In this image made available on Tuesday April 16, 2019 flames and smoke rise from the blaze as the spire starts to topple on Notre Dame cathedral in Paris, Monday, April 15, 2019. An inferno that raged through Notre Dame Cathedral for more than 12 hours destroyed its spire and its roof but spared its twin medieval bell towers, and a frantic rescue effort saved the monument's
Jean-Charles Forgeret poses next to photograph of Eugene Emmanuel Viollet-le-Duc, the renowned architect who designed the spire that was added to the medieval cathedral in the 19th century, in Charenton le Pont, outside Paris, Thursday, April 18, 2019. The reconstruction of Paris' Notre Dame Cathedral will rely on part on extensive plans drawn up in the 19th century for its last big renovation. Forgeret noted that the last restoration took 20 years, and cast doubt on the French president's 5-year deadline on fixing Notre Dame this time. (AP Photo/Nicolas Garriga)
Jean-Charles Forgeret poses with files related to Notre Dame cathedral in Charenton le Pont, outside Paris, Thursday, April 18, 2019. The reconstruction of Paris' Notre Dame Cathedral will rely on part on extensive plans drawn up in the 19th century for its last big renovation. Forgeret noted that the last restoration took 20 years, and cast doubt on the French president's 5-year deadline on fixing Notre Dame this time. (AP Photo/Nicolas Garriga)