While a host of French billionaires and companies offered donations worth around $1 billion, President Emmanuel Macron made a difficult promise – that the cathedral will be rebuilt within five years.
France will open the redesign of the Notre Dame cathedral's historic spire to international architects after Monday night's catastrophic blaze that gutted the oak-framed roof and sent the towering spire crashing through the vaulted ceiling.
The government's announcement on Wednesday added to a question many are asking as France grieves for its damaged national symbol – whether the familiar outline at the heart of the capital should be restored exactly as it was or given a modern twist.
The cathedral was built over nearly 200 years starting in the middle of the 12th century, although it was only in the mid-1800s that architect Eugene Viollet-le-Duc added the lead-covered spire during restoration work.
"The international competition will allow us to ask the question of whether we should even recreate the spire as it was conceived by Viollet-le-Duc," Prime Minister Edouard Philippe said.
"Or whether, as is often the case during the evolution of heritage, we should endow Notre Dame with a new spire that reflects the techniques and challenges of our era."
Monday's inferno devastated a world treasure, prompting an outpouring of collective sorrow and soul-searching in France over whether to recreate the destroyed rooftop and spire or adapt the cathedral to the 21st century.
The firefighters acted aggressively to protect wooden supports in the twin medieval bell towers from the flames, averting a bigger catastrophe, said Joss Vaz de Matos, a fire expert with France's Culture Ministry.
"If the fire reached this wooden structure, the bell tower would have been lost," de Matos said at a news conference.
"From the moment we lose the war of the bell towers, we lose the cathedral, because it's a chain-reaction collapse."
There was no immediate danger that the centuries-old structure would collapse but statues were also being removed to reduce the risk of movement, the fire service's spokesman said.
"Today, there is no risk of collapse. Our priority is to stabilise the pinnacles which are weakened, since they are no longer held up by the roof and its frame," Lieutenant-Colonel Gabriel Plus told Reuters.
There were also concerns for the towering mountain of scaffolding that had been erected prior to the blaze for repair work to the 90-metre (295-foot) spire, and that was subjected to intense heat, Plus said.
Matos told reporters that part of the triangular structure above the central rose window is to be taken down "to limit the movement" of the stone.
Matos said the main risk to the cathedral is the gables above the rose windows, which provide crucial support to the stained glass masterpieces.
He said the structure is particularly exposed to the wind, and the overall structure remains fragile.
Police officials told The Associated Press that the triangular structure is leaning 20 centimetres forward toward the street since the fire.
Doubts over Macron's five-year plan
Nearly $1 billion in donations have poured in for the vast restoration of the fire-ravaged Notre Dame cathedral — but a pledge by French President Emmanuel Macron that it will be completed within five years was facing accusations of being wildly off track.
Macron said the renovations to restore the iconic 19th-century spire, vaulting and two-thirds of the cathedral's roof would be completed in time for the Paris 2024 Olympics.
"We will rebuild the cathedral to be even more beautiful and I want it to be finished within five years," Macron said.
Experts have said, however, that the ambitious timeline appears insufficient for such a massive operation.
Even PM Philippe – while supporting the government timeline – acknowledged in an address on Wednesday that it would be difficult.
"This is obviously an immense challenge, a historic responsibility," Philippe said.
Tax break for smaller donors
It was not yet known what caused the blaze.
The city's public prosecutor, Remy Heitz, said on Tuesday there was no sign of arson and it was likely to have been the result of an accident.
Some 50 people were working on what would be a long and complex investigation, he said.
Passers-by laid flowers on bridges crossing the Seine River as Parisians gave thanks to see the bell towers standing valiantly after the fire.
Concerns over the cathedral's structural soundness have prevented investigators from entering Notre Dame's main nave to assess damage at ground level.
Philippe says the government will take a series of measures to secure the financing and accelerate the renovation work of the Notre Dame.
Speaking after a special Cabinet meeting dedicated to Notre Dame, Philippe said the government will present a bill next week to ensure "transparency and good management" during the reconstruction.
He said one measure will aim at ensuring that all donations actually end up going to Notre Dame.
The bill will also allow French ordinary citizens to get special tax cuts if they make a donation.