Notre Dame, the treasured Gothic jewel in Paris that went down in flames in 2019, will officially reopen on Saturday.

Immediately after the fire, French President Emmanuel Macron made an ambitious promise to restore the church within five years.

Here’s everything you need to know about the coming days.

What has happened so far?

On April 15, 2019, Notre Dame went up in flames. The cause of the fire remains a mystery. Investigators believe it was likely an accident – perhaps a burning cigarette or an electrical fault.

France – and much of the world – despaired as the roof of the 860-year-old cathedral collapsed, leaving the stone floor beneath covered in soot. Macron called it a “terrible tragedy” and vowed to rebuild the landmark church “because it is what our history deserves.” Some of the country’s wealthiest businessmen have pledged hundreds of millions of euros for the restoration.

Who was invited?

The guest list will be long and illustrious, but the most notable attendee will be Donald Trump. The US president-elect announced he would travel to Paris – his first trip abroad since last month’s election – in what he said would be “a very special day for everyone”.

Around 50 heads of state and government are expected to take part in the ceremony.

One notable absentee, however, will be Pope Francis. The Pope will travel to the French Mediterranean island of Corsica on December 15, just days after its reopening, but will forego a visit to the capital. A leading French archbishop said the “star” of the ceremony should be Notre Dame itself and that the pope did not want to distract from the occasion. The ceremony will also involve some 170 bishops from France and around the world, as well as a priest from each of the 106 parishes of the Paris diocese.

What’s going on on Saturday?

Macron will deliver a speech outside the cathedral around 6 p.m. (12 p.m. ET). Paris Archbishop Laurent Ulrich will then bang on the cathedral’s locked doors with his crook, an ornate staff. As soon as the doors open, the cathedral “responds” to the knock by chanting Psalm 121 three times, which begins, “I will lift up my eyes to the hills.” Then the doors open.

The ceremony then proceeds in three parts. Firstly, the “awakening” of the great organ – the largest in France, with 8,000 pipes and 115 stops. Secondly, the “Song of Office” – a series of psalms and prayers, including the Lord’s Prayer. The archbishop then gives the final blessing and the choir sings Te Deum, a Latin hymn. Following the service, France TV will broadcast a program about the reconstruction of the cathedral.

Read more about the reopening of Notre Dame.