France marked the second anniversary of the Notre Dame fire as architects finalised the start of its restoration programme.
Since the fire destroyed much of the cathedral's roof and caused its spire to collapse, the extensive rebuild has focused on consolidation, after which restoration work will begin.
French President Emmanuel Macron said that while a lot of good work had been accomplished in the past two years, "we also see what remains to be done".
Mr Macron set a five-year restoration target in the immediate aftermath of the fire, which, if met, would make the cathedral accessible by the time Paris hosts the Olympics in summer 2024.
The aim for a “return to worship” is still in place, but some parts of the rebuild could take up to 20 years.
On Thursday, the interior of the cathedral was encased in a web of scaffolding, surrounded by nets and tarpaulins, where carpenters, rope workers, scaffolders and crane operators worked in tandem.
Metals melted in the fire had to be cut from the roof and the vaults inside the cathedral needed to be stabilised.
"The objective … is to return Notre Dame to worshippers and to visits in 2024. That means ... Mass will be able to be organised in the cathedral," said Jeremie Patrier-Leitus, a spokesman for the restoration.
"Notre Dame is holding up, it is still there. We are all gathered and mobilised to restore the cathedral and give this jewel of French Gothic architecture back to the world."
Notre Dame two years on
Illustrating the vast amount of work still to be done, 1,000 oak trees were felled in 200 French forests this spring to construct the frame for the cathedral’s transept and spire.
“I can say today that the cathedral is saved. It is well secured and we can now do the huge work of reconstruction that is not going to destabilise the whole building,” said Notre Dame’s rector, Patrick Chauvet.
