“Most of these great cathedrals become destination points through the treasury, what they hold that you can come and worship or that you can come and see,” said Nora Heimann, a professor of art history at the Catholic University of America.

The rose windows

The cathedral contains three rose windows whose stained-glass panes, shaped like flower petals, each tell a religious story, including scenes from the Old and New Testaments, stories from the lives of the Twelve Apostles, and the resurrection of Christ.

The biggest of the windows is over 42 feet wide and has become a major tourist attraction.

On Monday night, Benoist de Sinety, a bishop of the Archdiocese of Paris, said that high heat had damaged the windows, melting the lead that held their panes in place. But Mr. Riester, speaking at a news conference in Paris at midday Tuesday, gave a more optimistic prognosis. “The large rose windows don’t appear to have suffered catastrophic damage,” he said.

Aline Magnien, who leads the French government’s Research Laboratory for Historical Monuments, said in an email on Tuesday afternoon that the oldest examples of stained glass “seemed to be saved.” But, she added, “We don’t know many things about the other ones from the 20th century.”

Relics of the patron saints of Paris

The spire of the cathedral, which collapsed on Monday, contained the relics of St. Denis and St. Geneviève, the patron saints of Paris. Laurent Ferri, a curator in the Rare and Manuscript Collections at Cornell University, said an archbishop placed them there in 1935 to protect the building.