Explained | What to know as Notre Dame reopens

Paris: Notre Dame Cathedral in Paris is set to reopen after 5-1/2 years of work to restore its wood and lead roofing, famous spire and other parts of the building that were destroyed or damaged in a devastating fire in April 2019.

Here is everything you need to know.

When is Notre Dame reopening?

An official and religious ceremony will take place Saturday.

First, President Emmanuel Macron of France, who had vowed to restore the Gothic medieval masterpiece within five years of the fire, will give a speech in front of the cathedral to Roman Catholic dignitaries, foreign officials and donors who contributed to the renovation.

Afterward, the archbishop of Paris will strike the doors of the cathedral with his staff, and a choir will sing Psalm 121 three times. The doors will be opened, and the archbishop will lead a religious service and bless the great organ, which was not damaged but had to be cleaned of toxic lead dust.

Next will come a televised show and concert, also in front of the cathedral. Gustavo Dudamel will conduct the Radio France Philharmonic Orchestra, and there will be performances by Chinese pianist Lang Lang, Beninese-French singer Angélique Kidjo, Canadian singer Garou and others.

On Sunday, the cathedral will celebrate a Mass to consecrate the altar. Macron and about 170 bishops from France and elsewhere are expected to attend, as well as priests from Paris' 106 parishes.

A Mass for the general public will be offered in the evening -- that will be the first time visitors will be able to enter the renovated cathedral.

Who is attending the ceremonies?

More than 40 heads of state and government, religious dignitaries, and other officials are expected to attend, but Pope Francis has already said that he will not be present.

President Joe Biden is also not expected to attend, but Jill Biden, the first lady, will be there. President-elect Donald Trump said this week that he would also make the trip.

Authorities have planned extremely tight security for the area around Notre Dame over the weekend, similar to the arrangements for the Summer Olympics opening ceremony. A limited number of the general public will be able to watch from farther away on giant screens.

What else is planned?

From Dec. 9-15, there will be Masses for the firefighters who saved the building, for the workers and artisans who helped to renovate it and for the 340,000 or so donors who provided money for the renovation, as well as other Masses for the general public. Two concerts, with performances of Johann Sebastian Bach's Magnificat, will be held in the cathedral Dec. 17 and December 18.

When can I visit?

All slots to attend the Sunday public Mass have already been booked. But, beginning Monday, the cathedral -- which was one of the French capital's most visited monuments before the blaze shut it down -- will be open to the public. It will begin accepting pilgrimage groups in February and tour groups in June.

Will visiting be free of charge?

Yes. France's culture minister had floated the idea of an entrance fee this fall to help pay for the expensive upkeep of the country's thousands of churches and other religious monuments. Many of them belong to government authorities -- a legacy of the French Revolution, when property belonging to the clergy was nationalized. Notre Dame, for instance, is owned by the French state.

But the Roman Catholic Church of France runs the monument, and it opposed any entrance fee. The church's mission is to "welcome every man and woman unconditionally, and therefore necessarily free of charge, regardless of their religion or belief, opinions, or financial means," church officials said in October.

What did the renovation involve and how much did it cost?

About 840 million euros, or $900 million, from around 340,000 donors poured in after the fire to help renovate the cathedral.

Notre Dame came dangerously close to collapsing during the blaze, and the first step was to secure it. Workers also had to deep-clean the limestone, paintings and statues to remove ash, lead particles and centuries of accumulated grime.

The effort involved about 250 companies and roughly 2,000 workers and artisans, including architects, carpenters, engineers, stonecutters, painters, gold-leaf decorators, steeplejacks, crane operators, organ cleaners and roof coverers. They restored stained-glass windows, created new lead roof ornaments, hewed log beams and dry-fit roofing trusses, among other work. At the peak, up to 600 workers clambered around scaffolding every day, laboring under stringent measures to avoid exposure to toxic lead dust.

Did Notre Dame get a modern twist?

No. The French government had suggested that the cathedral's 19th-century spire could be rebuilt with a "contemporary architectural gesture" and had even proposed an architectural competition, leading to a flurry of ideas that ranged from daring to outlandish, including a beam of light and a carbon-fiber flame.

But the idea of a modern spire was never popular, Macron never committed to it, and it was dropped. The spire was rebuilt as it was: an oak framework covered in lead, topped by a cross and a copper rooster that overlook Paris more than 300 feet above ground. The medieval attic, a lattice of ancient oak beams known as "the forest," was also restored to its original state.

The renovation did, however, add modern fire protections in the roofing that were absent in 2019, including misting devices, firewalls, thermal cameras and thicker roof boards that burn more slowly.

Is work on Notre Dame done?

No. Exterior renovations will continue for several more years. A sum of about $150 million that remains from the donations will be used to restore sections including the sacristy and the flying buttresses, which were worn out well before the fire.

Do we now know what caused the fire?

Not exactly. French authorities have uncovered no evidence of arson and say that an accidental cause is most likely, possibly tied to restoration work on the spire that was being carried out when the fire occurred.

An investigation is continuing and could last for at least several more months, according to the Paris prosecutor's office. Leading theories are that the blaze was sparked by a discarded cigarette or by a short circuit, possibly in the electrified bells of the spire or in elevators used by workers.

But no one has been charged, and a definitive explanation may never be determined.