The singers were unseen, filling the grand darkened space of Paris’ Saint-Eustache Church with song, like disembodied angels. They moved slowly in procession, up the aisles to a makeshift stage, where they revealed themselves: the men, women and children of the Notre Dame Cathedral choir.

It has been more than 2-1/2 years since fire tore through Notre Dame, the most visited church in the world and France’s most visited monument. The herculean task of restoring the medieval masterpiece was then delayed by the pandemic, but the French president has promised that the cathedral will reopen in time for the 2024 Paris Olympics.

The musical tradition at Notre Dame is as old as the cathedral itself, with origins dating back to the 12th century.

But since the fire, the cathedral’s ancient music school and its choirs, called the Maitrise of Notre Dame, has struggled financially: the state and the city of Paris eliminated funding; the school lost one-third of its 2 million-euro annual budget and had to fire most of its staff and musicians.

“We went through a period of deep mourning, but now we are motivated by the certainty that Notre Dame will one day reopen,” said Yves Castagnet, the master organist who has played at Notre Dame for 33 years. “Meanwhile, our mission is to preserve and spread the spirit of our great cathedral outside its walls. We have become the city’s ambassadors of sound.”

The musicians now perform like a band of musical nomads, awaiting their return home. Tourists — whether believers or not — who had made the Cathedral a pilgrimage site have been left bereft. The sense of loss is especially acute during the Christmas holidays, when Notre Dame’s midnight Christmas Mass doubled as a glorious organ and choir concert. But there is a foolproof way to emulate the joy and comfort previously found at Notre Dame: Follow the music.

The cathedral’s closure has opened many visitors to a world overlooked even by Parisians themselves: the city’s more than 100 churches. Most of these have some music accompanying Mass and Vespers; some attract master organists and choirs, who perform both scheduled and impromptu concerts — especially at Christmastime. Every church has at least one Christmas Mass, but even churches that don’t regularly host concerts are likely to offer liturgical music at the end of December.

The cultural scene in Paris came back to life this fall, but now the uncertainty of the omicron variant has cast a long shadow over the city. Entry into all indoor spaces requires the presentation of a “pass sanitaire” (proof of vaccination, or a negative PCR or antigen test no more than 3 days old). Masks must be worn indoors. On Dec. 6, the CDC issued a Level 4 “do not travel” notice for France, indicating a very high level of COVID-19 in the country. The French government has decided to keep most public spaces, including restaurants, bars, museums — and churches — open over the holidays, but it is advisable to verify whether an event has been canceled.

Many of Paris’ churches have musically extraordinary organs (and organists) even if they do not also have a choir. Nearly 20 churches scattered across the city have organs made by Aristide Cavaille-Coll, a 19th-century master organ maker, whose innovations ushered in a new era of organ construction and sound. Notre Dame’s own Cavaille-Coll organ has been under repair since the fire.

From musical Mass and Vespers to open-door visiting hours, churches are free and open to the public — though best practice is to bring a 2-euro coin to drop in a donation box. Concerts that are hosted rather than organized by churches will charge for tickets and they are best booked in advance.

Here’s where to find the musical spirit of Notre Dame this holiday season.

Wandering choirs

Five Paris churches are playing host to the Maitrise while Notre Dame is under reconstruction. One of Paris’ oldest churches, Saint-Germain-l’Auxerrois, is a 15-minute walk along the Right Bank of the Seine and across the street from the Louvre. The cathedral’s religious services have moved there for the duration, along with some of its music.

Rebuilt many times over the centuries, the church is the resting place for many of France’s poets, architects, painters and sculptors. It is a visual ­adventure that blends several styles: a Romanesque bell tower, a High Gothic chancel, a Flamboyant nave, a Renaissance portal and a Flemish altarpiece and triptych carved in wood.

Vierge du Pilier, the most important statue of Mary to which people came to pray at Notre Dame, is on display here. One of Paris’ most beautiful church organs is here — a 32-stop masterpiece built in 1771 by Francois-Henri Clicquot. It is undergoing restoration, but may be ready for Christmas. For now, Castagnet plays on a modern auxiliary organ installed near the main altar.

Accompanied by the Maitrise, the 5:45 p.m. Monday through Saturday Vespers and the 6:30 p.m. Sunday Mass are broadcast on Catholic television’s YouTube channel. On Sundays, the 6:30 p.m. Mass and the 10 a.m. Gregorian Mass are broadcast on Notre Dame Radio. On Christmas Day, the Maitrise is expected to perform during the 11:30 a.m. Mass, as well as the 10 a.m. Gregorian Mass. Plans for the usual Christmas Eve performance are uncertain because of COVID-19 considerations.

But Saint-Germain-l’Auxerrois is too small to host to concerts with the Maitrise’s large choirs, which have struggled to find other Paris churches willing to host them. About twice a month, they perform in other venues, especially at two of Paris’ best-known churches, both of them about a mile away: Sainte-Eustache near the Forum des Halles on the Right Bank, and St.-Sulpice (bigger than Notre Dame), in the Saint-Germain-des-Pres neighborhood on the Left.

Saint-Eustache is considered a jewel of the French Renaissance, but it also can be seen as a mini-Notre Dame. Its interior — including its perpendicular nave and transept and side and radial chapels — was modeled on the great Gothic cathedral. With its extraordinary acoustics, Saint-Eustache regularly hosts concerts — from psalms to contemporary compositions. Even the ordinary singing of parishioners during weekend services stirs the soul. The 11 a.m. Sunday Mass features both the church chorus and the organist, Thomas Ospital; there is also an organ concert at 5 p.m. on Sundays.

The church, host to other groups besides the Maitrise, will be the venue for two planned classical music concerts at the end of the year, one on New Year’s Eve, and the other on Jan. 1.

Saint-Sulpice is a late ­baroque building, constructed over the 13th-­century foundations of a Romanesque church. If you want a 19th-century Eugene Dela­croix fix, this is the place to go: two of his paintings and a ceiling fresco (magnificently restored) grace this venue. And it is just as famous for its renowned organ.

In addition to Masses at regular hours, an 11 p.m. Mass on Christmas Eve, a Christmas concert on Thursday (from 15 to 30 euros, or about $17 to $34 based on current exchange rates), and a New Year’s Eve concert on Dec. 31 (from 44 to 66 euros) are planned.

The Notre Dame choirs are also performing at Saint-­Etienne-du-Mont, a gothic structure in the Latin Quarter at the top of a gentle hill honoring Genevieve, Paris’ patron saint. Her mystical ­piety, fasting and shrewd ­negotiating skills are said to have stopped Attila the Hun from invading Paris in the fifth century.

Saint-Etienne-du-Mont is most famous for Paris’ only “rood screen,” an intricately carved, lofted-arch, 16th-­century partition that serves as a decorative barrier between the high altar and the congregation.

Then there is its 17th-­century organ, considered one of the finest in Paris, updated by Cavaille-Coll in 1863, and restored several years ago.

This Christmas, the church has organized a play recounting the story of Saint Genevieve’s life (scheduled to run until Sunday; reservations necessary). Although no concerts are scheduled here for Christmas, the church’s organists will play at holiday Masses.

Finally, the Notre Dame choirs can be heard from time to time at Saint-Severin in the Latin Quarter — not far from the cathedral and the Shakespeare and Company bookstore. Saint-­Severin was built in the late Gothic style in the 11th century. The Maitrise will be at Saint-Sulpice and Saint-­Germain-l’Auxerrois this Christmas. Saint-Severin plans to offer two classical concerts: the predominantly string orchestra Les Solistes Francais on Christmas Day, and a trumpet and organ recital on New Year’s Day.

Organs and more

Paris has more Cavaille-Coll church organs than any other city in the world — and many of these are not far from Notre Dame. The Sainte-Clotilde Basilica, on the Left Bank near Les Invalides, is a beautiful space to go in and pray, and there is a concert on the 1859 Great Organ every second Saturday of the month (except in August) at 5 p.m. The Basilica’s choir also practices Saturdays from 5 to 6 p.m. in the Las Cases room, and on Sundays starting at 10 a.m., before its participation in the 11 a.m. Mass.

Saint-Roch, an 18th-­century church boasting a museum-worthy art collection, 10 minutes from the Louvre, has an early (but no less excellent) Cavaille-Coll, from 1842. On Mondays from 12:30 to 1:15 p.m. there are “Musical Monday” concerts when you can hear the organ; you can also hear it at some Masses.

A Cavaille-Coll organ and the Notre Dame choirs are not the only markers of a great Paris church music experience. On the Left Bank’s Boulevard St.-Germain is Saint-Germain-des-Pres Church. This church with delicious acoustics is the oldest in Paris, founded by King Childebert I in 543, restored many times and now completing a major multiyear renovation.

On Christmas Eve at 10 p.m. a musical prelude to the 10:30 p.m. Mass is scheduled. On Dec. 25-26, the planned Masses are at 11 a.m. and 7 p.m., during which traditional music will be sung with the Christmas liturgy. There is also a Christmas concert scheduled on the 25th at 3:30 p.m. (no reservation necessary and free, though a donation is encouraged).

Some churches with high tourist appeal offer concerts of uneven excellence. Sainte-Chapelle, just steps away from Notre Dame on the Ile de la Cite, advertises concerts with a recognizable repertoire (Vivaldi’s Four Seasons is a favorite). The performances are considered good enough — for tourists. The cost is not insignificant: about $70. Pay $10 more for a coupe of Champagne.

From today through Dec. 30 (except Christmas Day) Christmas concerts are planned at Sainte-Chapelle; also, two New Year’s concerts, on Dec. 31 and Jan. 2. (Some dates have already sold out.)

Sainte-Chapelle has not been used as a church since the French Revolution, but like Notre Dame, is one of the world’s most glorious examples of Gothic architecture, and it still resembles the grand place of worship it once was.