The reopening this weekend of Notre Dame is a succession of ceremonies to breathe life back into the iconic cathedral and celebrate the recovery from its devastating fire in 2019.

High points will be the ritualised reopening of the cathedral's massive doors, the reawakening of its thunderous organ and the celebration of the first Mass. For both France and the Catholic Church, the televised and tightly scripted ceremonies will be an opportunity to display can-do resilience and global influence.

US President-elect Donald Trump and dozens of heads of state and government accepted invites from French President Emmanuel Macron. The Catholic faithful are so eager to worship again inside Notre Dame that tickets for the first week of Masses were snapped up in 25 minutes, the cathedral's rector says.

During part one of Notre Dame's rebirth on Saturday evening, Archbishop Laurent Ulrich will lead more than 1,500 guests through a reopening service. Part two, on Sunday, is an inaugural Mass, with special rites to consecrate the main altar.

Open, great doors

On Saturday, Ulrich will first reopen Notre Dame's great doors — by tapping them with his crosier, or bishop's staff.

The staff was created for the occasion by designer Sylvain Dubuisson. The wood — bearing visible black traces from the blaze — was made with pieces of the cathedral roof that collapsed in the inferno, Dubuisson told The Associated Press.

In response to the archbishop's door-knocks, the cathedral will erupt into song, its choirs once again filling the cavernous spaces.

That back-and-forth will happen three times. The doors will then open so guests can stream inside past their sculptures of biblical figures.

Reawakening the great organ

The voice of Notre Dame's great organ hasn't been heard in public since the blaze coated the nearly 8,000 pipes with toxic dust released when the lead roofing burned.

After the door-opening rites, Ulrich will reawaken the giant instrument. He'll address it directly with a series of eight incantations, starting with “Awaken, organ, sacred instrument: Sing the praise of God."

That prompt will launch a conversation with the organ, with four organists (Olivier Latry, Vincent Dubois, Thibault Fajoles and Thierry Escaich) taking turns to play its responses.

They'll be perched high above the congregation, seated at the newly renovated giant console that controls the instrument — through five keyboards of 56 notes each, foot pedals for 30 notes, and 115 stops.

Off-the-cuff responses

Latry says he and the other organists will improvise their responses to the archbishop's prompts — depending on their own and the congregation's mood.

“Since it's improvisation, you really need to feel the moment,” Latry told AP.

“When I am there, I will know what I am going to do. Before that, I simply have a few ideas but the ideas are not fully formed — because they will change depending on the atmosphere, the lighting, the people who'll be down below, their reaction."

The organ has a vast palette of sounds to play with. The deepest of its 7,952 pipes are as large as a human torso, producing a low rumbling sound. The smallest are no larger than a pen.

The painstaking re-tuning of the organ — after it was dismantled, cleaned and put back together — took around six months, with tuners working at night so they could tweak the notes in silence.

Billionaires and poor Parisians among the guests

Before the fire, efforts to fund renovations of the nearly 900-year-old cathedral had been struggling. But that changed with the blaze.

“We had an outpouring of support," says fund-raising committee member Michel Picaud. “I received 400 donations an hour, so my smartphone completely crashed.”

In all, 340,000 people from more than 150 countries donated 846 million euros (US$364 million), the public body in charge of Notre Dame's restauration says. The support testifies to global affection for the monument that transcends frontiers and faiths.

“It's something which belongs to everybody,” Picaud told AP. The nonprofit he leads, Friends of Notre-Dame de Paris, has raised $57 million from 50,000 international donors, most of them Americans.

“It's not only a Parisian cathedral or monument," he said. "All over the world, I think, people have the feeling that this is part of their — I would say — heritage."

At the reopening, billionaire donors from France and beyond will rub shoulders with other guests far less fortunate.

They'll include “the poorest among Parisians, all those who are helped by charitable associations and who will be several hundred inside the cathedral,” Rev. Olivier Ribadeau Dumas, Notre Dame's rector, told AP.

Primped for the occasion

Although construction work continues outside, the restored interiors look more magnificent than they have for generations.

The limestone walls are creamy and luminous, cleaned of years of accumulated grime. Vaulted ceilings that collapsed have been repaired. The archbishop and other members have new garments, from a designer who has also dressed Beyoncé, Rihanna and others. The cathedral also has new furniture, including a new altar to replace one crushed when the flaming spire collapsed.

The rector says “no one alive has seen the cathedral” as it looks now.

“The blondness of the stone, the brilliance of the paintings, the light through the stained glass windows, all the artworks, all the paintings, that were cleaned, the statues that were restored," he said.

“All of that did not exist before the fire.”