On Monday, the fire raged through the cathedral for more than 12 hours, ultimately destroying its spire and roof but sparing its twin medieval bell towers. As the blaze roared, there was a frantic effort to rescue the monument's "most precious treasures," including the Crown of Thorns said to have been worn by Jesus.

Remarkably, no one was killed in the blaze, which occurred during a Mass, after firefighters and church officials speedily evacuated everyone inside.

A day after the inferno, French President Emmanuel Macron set an ambitious goal of rebuilding the famed cathedral "even more beautifully" in five years. Since then, donations have been pouring in all over the world. It surpassed the $1 billion mark Wednesday.

The rector of Notre Dame Cathedral has also proposed building a small, temporary church on the plaza outside the monument so that the faithful have a place of worship while the cathedral is closed for renovation.

"We mustn't say 'the cathedral is closed for five years' and that's it," Monsignor Patrick Chauvet told France's CNews television channel. "Can I not build an ephemeral cathedral on an esplanade (in front of Notre Dame)?"

On Thursday, workers were seen securing the support structure above one of Notre Dame's famed rose windows with wooden planks.