Old Montreal (French: Vieux-Montréal, pronounced [vjø mɔ̃ʁeal]) is a historic neighbourhood within the municipality of Montreal in the province of Quebec, Canada. Home to the Old Port of Montreal, the neighbourhood is bordered on the west by McGill Street, on the north by Ruelle des Fortifications, on the east by rue Saint-André, and on the south by the Saint Lawrence River. Following recent amendments, the neighbourhood has expanded to include the Rue des Soeurs Grises in the west, Saint Antoine Street in the north, and Saint Hubert Street in the east.

Founded by French settlers in 1642 as Fort Ville-Marie, Old Montreal is home to many structures dating back to the era of New France. The 17th century settlement lends its name to the borough in which the neighbourhood lies, Ville-Marie. In 1964, much of Old Montreal was declared a historic district by the Ministère des Affaires culturelles du Québec.

In 1605, Samuel de Champlain established a fur-trading post at Place Royale (Old Montreal) at the confluence of the Saint Lawrence River and the Petite Rivière St-Pierre, a former river in the area. It was adjacent to present-day Place D'Youville and the Pointe-à-Callière Museum. However, the settlers were later forced to abandon the outpost due to incursions by the Iroquois.^{[citation needed]}

The original settlement of Montreal was founded in 1642. It was known as Ville-Marie, and was located in roughly the same location as the trading post set up by de Champlain. The founder, Paul Chomedey de Maisonneuve, built a fort in 1643 which would serve as the headquarters for the Société Notre-Dame de Montréal, an organization whose mission was to convert members of First Nations to Christianity and establish a Christian settlement in New France. The company in charge of managing the settlement was founded by the Sulpician Jean-Jacques Olier and by Jérôme Le Royer (Sieur de La Dauversière).

After the Société Notre-Dame dissolved on March 9, 1663, the Sulpicians (who arrived in 1657) became the Seigneurs of Montreal, as King Louis XIV of France took personal control over the colony. The new system gave them the island of Montreal, with the obligation to live there and ensure its development by cultivating the land. In 1665, Louis XIV sent 1,200 men from the Régiment de Carignan-Salières. The Sulpicians organized seigneuries at the centre of the island. François Dollier Casson established the first grid of streets in the colony, following the paths of existing trails. These early streets included the Rue Notre-Dame, the Rue Saint-Paul and Rue Saint-Jacques. Buildings of the era include the Hôtel-Dieu de Montréal, the Saint-Sulpice Old Seminary and Notre Dame Church (replaced later by the Notre-Dame Basilica).

In the early 18th century, the name "Montreal" (which originally referred to the mountain Mont-Royal) gradually replaced that of Ville-Marie. The arrival in 1657 of Marguerite Bourgeoys (who founded the Congregation Notre-Dame) and the arrival of the Jesuits and Recollets in 1692, helped to ensure the Catholic character of the settlement. The original fortifications of Montreal, erected in 1717 by Gaspard Chaussegros de Léry, formed the boundaries of Montreal at the time. De Léry had the fortifications constructed to secure the settlement from a British invasion and to allow future expansion inside the walls. Though the walls may have provided security from invasion, they created a different problem: a large concentration of wooden houses (with fireplaces) led to many devastating fires. In 1721, Montreal received a royal order from France to ban wood construction; buildings were to be constructed using stone, but the ban was never fully respected.

Canada (New France) became a British colony in 1763 after the Seven Years' War. British rule radically changed the face of Old Montreal, partially due to significant fires that destroyed much of the city and provided the British with a mandate to rebuild it. In May 1765, fire destroyed about 110 houses before destroying the old Hôtel de Callière and the former General Hospital. In April 1768, 88 houses between rue Saint-Jean-Baptiste and Hotel Vaudreuil were burned, including the Congregation Notre-Dame convent. Between the two fires, nearly half of the buildings in the city were destroyed. In the following years, the city was rebuilt even more densely. On June 6, 1803, a massive fire destroyed the prison, the church and the dependencies of Jesuits, a dozen houses and the Château Vaudreuil. Two speculators bought the Château's gardens, offered one-third to the city, and divided the rest into seven lots of their own. The city's oldest public monument, Nelson's Column, was erected in 1809 on part of the former garden plot and given to the city. This space became the new market square, called Marché Neuf (New Market) before assuming its present name of Place Jacques-Cartier in 1845. The space occupied by the church of the Jesuits became the Place Vauquelin and Montreal City Hall arose from the old Jesuit gardens in 1873.

In 1812, a fire destroyed the luxurious Mansion House hotel, which had been popular with the Beaver Club and had housed the first public library in Montreal. It was replaced by the British-American Hotel, which contained the John Molson-built Royal Theatre, the city's first permanent theatre. The hotel burned in 1833, and was rebuilt in 1845 at the Bonsecours Market. In 1849, a riot caused a fire with political consequences when, protesting against a law, a Tory crowd burned down the Parliament building in the old Marché Saint-Anne on Place d'Youville. The site of the Parliament fire housed Montreal's first fire station in 1903; the building still exists as the Centre d’histoire de Montréal.