By 1824, Montreal's original parish church of Notre-Dame, built on the same site in 1672, could no longer contain its growing congregation. The Sulpician order, who had governed the parish since their arrival in 1657, needed a replacement that could seat up to 10,000 worshippers. They turned not to a local architect, not even to a Catholic, but to James O'Donnell -- an Irish-American Anglican working out of New York City. O'Donnell was a passionate advocate of the Gothic Revival movement, and he poured that conviction into every pointed arch and soaring vault. He envisioned twin towers tall enough to be seen from any point in the city, and a terrace ringing the exterior that was never completed due to lack of funding. The cornerstone was laid at Place d'Armes on September 1, 1824, and the sanctuary was finished by 1830. O'Donnell did not live to see the towers completed -- the first rose in 1841, the second in 1843, finished by English-born architect John Ostell following O'Donnell's original plans. Upon completion, it was the largest church in North America, a distinction it held for over fifty years. O'Donnell himself converted to Roman Catholicism on his deathbed, ensuring he could be buried in the crypt he had designed. He remains the only person interred there.

Most churches fill their stained glass windows with scenes from the Bible. Notre-Dame Basilica did something unusual: its windows depict the religious history of Montreal itself. The arrival of the Sulpicians. The founding of the parish. The spiritual milestones of a young colony. Inside, the effect is less like entering a house of worship and more like stepping into an illuminated manuscript of the city's past. Hundreds of intricate wooden carvings line the walls, each one hand-finished. The Casavant Freres pipe organ, completed in 1891, commands the space with 7,000 individual pipes, four keyboards, 99 stops, and an adjustable combination system -- notably the first organ with adjustable-combination pedals operated by electricity. Behind the main sanctuary, a more intimate space once existed: the Chapelle du Sacre-Coeur, the Chapel of the Sacred Heart, completed in 1888. Arson destroyed it on December 7, 1978. The rebuilt chapel preserved the first two levels from old drawings and photographs, but crowned them with a modern bronze altarpiece by Quebec sculptor Charles Daudelin, merging old and new in a single sacred space.

Notre-Dame Basilica has served as the stage for some of Canada's most significant public moments. On May 31, 2000, thousands gathered inside and outside the basilica for the provincial state funeral of Maurice "Rocket" Richard, the Montreal Canadiens legend. Five months later, on October 3, 2000, a young Justin Trudeau stepped to a lectern near the High Altar to deliver the eulogy for his father, Pierre Trudeau, Canada's 15th prime minister. The basilica hosted the December 17, 1994 wedding of Celine Dion and Rene Angelil, and later the funeral service for Angelil on January 22, 2016. Most recently, on March 23, 2024, the state funeral of Brian Mulroney, Canada's 18th prime minister, filled the nave. It is a tradition among many Montrealers to attend the annual performance of Handel's Messiah here every Christmas, the music swelling beneath those blue and gold vaults. Pope John Paul II elevated the church to the status of a minor basilica on April 21, 1982. It was designated a National Historic Site of Canada in 1989.

The West Tower, named La Perseverance, holds a bourdon bell nicknamed Jean-Baptiste. Cast in 1848 at John Dod Ward's Eagle Foundry, it weighs 10,900 kilograms and tolls only on special occasions -- funerals, great church festivals, and Christmas Eve. The East Tower, La Temperance, houses a ten-bell carillon from the same foundry, cast in 1842. When Jean-Baptiste rings out across Old Montreal, its deep resonance carries over the rooftops and down to the waterfront, a sound that has punctuated the city's most solemn and joyful moments for nearly two centuries. From above, the twin towers of Notre-Dame stand out against the modern skyline of downtown Montreal, their Gothic silhouettes unmistakable from altitude. The basilica sits at the foot of the old city, just north of the Saint Lawrence River, a stone anchor connecting Montreal to the faith and ambition of its earliest settlers.