Notre-Dame's twin towers have served as an Old Montreal landmark since the Neo-Gothic basilica was finished in 1829. Today they continue to be the focal point, where tourists disembark from buses and calèche drivers line up for passengers. The interior glows with gilded statuary and gold-leafed fleurs de lys, and is home to one of the largest pipe organs in the world. The Montreal Symphony Orchestra performs its Christmas production of Messiah here at the Basilique Notre-Dame de Montréal or the Notre-Dame Basilica.

Christ Church Cathedral is nestled within the central region of the city and has been serving it since the early 19th century. Designed by famed architect Frank Wills, Christ Church Cathedral is a great example of 19th-century Neo-Gothic architecture. Inspired by the Gothic-style churches of the 14th century, the cathedral displays some impressive architecture through intricate designs and awe-inspiring stone-work. Its aluminium steeple, square crossing tower and stone spire are some of its key features, which were considered a rare sight in its time.

Plans for the construction of the Mary, Queen of the World Cathedral first began in 1852, soon after Saint-Jacques Cathedral was destroyed by fire. At the behest of Ignace Bourget, the architect Victor Bourgeau was assigned the ambitious task of designing a cathedral in the image of the magnificent St Peter's Basilica in Rome. The architectural masterpiece was completed in 1894 and is renown today as one of Quebec's most revered religious sites. Inside a spectacular baldachin adorns the altar and elaborate paintings depict the early history of Montreal, while outside exquisitely wrought statues of the city's 13 patron saints watch over the people, replacing the 12 statues of Christ's apostles that adorn the exterior walls of St Peter's Basilica. The cathedral remains a sacred place of worship even as it attracts droves of tourists who are drawn to its austere beauty and artistic treasures.

Famous architect Georges-Alphonse Monette outlined the Church of Saint-Léon-de-Westmount also known as Église Saint-Léon de Westmount and constructed it in 1901. It was made with a technique called buon fresco that is used by applying wet plaster. The building has a trademark Italianate facade, bell tower and is a classic example of Romanesque Revival style of architecture. The glass windows are colorfully painted. In 1997 the church was registered in the National Historic Site of Canada.

Saint Joseph's Oratory in Montreal is the nation's largest church, its regal dome second in height only to St. Peter's Basilica in Rome. A small chapel dedicated to Saint Joseph was built at the site in 1904 by Brother André, renowned for his miraculous ability to heal the injured and ailing. He was later beatified in 1982 and canonized in 2010. Completed in 1960, the renaissance church that replaced the original shrine encompasses a basilica, a votive chapel lined with discarded crutches, and the heart of Brother André amongst several other treasures. Outside, the Stations of the Cross grace the sculpture garden where scenes from the film Jésus of Montréal were shot. The oratory itself is a striking beauty that dominates the skyline for miles around, its elegant dome rising high above the bucolic scene. One of the world's most revered Catholic shrines and an important place of pilgrimage, Saint Joseph's Oratory inspires wonder in the hearts of the devout and the simply curious.