The iconicNotre Dame Cathedralin Paris is scheduled to reopen on Saturday, Dec. 7, after a massive fire caused significant structural damage — including a collapsed roof — in April 2019.

The in-depth restoration process took more than 2,000 days of labor and involved over 2,000 people, with many of France’s wealthiest citizens pledging money to help rebuild the historical and cultural landmark, according toCNN.

While thesource of the fire remains a mystery, investigators believe it may have been caused by an electrical issue or perhaps even a lit cigarette. After the devastating fire, French PresidentEmmanuel Macron pledged to restore the site within five years.

While COVID slowed progress for much of 2020, workers successfully removed much of thecharred scaffolding that had been in place from a previous repair project, an important first step.

That same year saw efforts to restore the cathedral’s legendary organ, which is France’s largest musical instrument. While the organ — which features8,000 pipes — was technically not damaged by the fire, it had been coated in toxic debris. 

By 2021, project managers selected the first historic French oak trees to begin rebuilding the structure’s signature spire. The trees were gathered from Bercé forest in the French Loire region. Master craftspeople also worked on securing the structure that same year, which entailed fashioning a giant temporary “umbrella” to keep the interior of the cathedral safe while further repairs were made.

The following year in 2022, expert glassmakers and locksmiths from all across the country — and even several from abroad — arrived to begin restoring the cathedral’s famous stained glass windows. 

In 2023, several pivotal moments in the restoration process took place, including the sudden death of the army general who had been selected to oversee the project,General Jean-Louis Georgelin. President Macron honored Georgelin, calling him the “greatest soldier” in championing the restoration. 

That same year, agolden rooster — an official symbol of France — was placed atop the building’s new spire. The rooster was fashioned to also resemble a phoenix to signify the cathedral’s rebirth. Religious relics were placed inside the golden animal to serve as a time capsule, according to theAssociated Press.

February 2024 entailed the removal of the longstanding scaffolding on the structure, with the ensuing months marking the final stretch of the restoration.

The reopening ceremony will take place on Dec. 7, and more than 50 heads of state are expected to attend, including U.S. President-electDonald Trump. The U.K.’sPrince William will also be in attendance, standing in for his father,King Charles, as he continues to undergo treatment for cancer.

After the ceremony, the cathedral will hold two daily masses for eight consecutive days, with several of the masses open to the public. The cathedral is free to visit and will then remain open to the public indefinitely.