Montreal is renowned as an artistic oasis, a hedonist's haven, a hotbed of sin. It is also the country's most livable city.

Montreal's incredible habitability lies in the architectural composition of its great neighbourhoods. These communities envelop without suffocating, striking the perfect balance of scale and density. Where a sparse city becomes grey and alienating, Montreal remains cozy in the long winters. Where a vertical city overwhelms, Montreal allows you to breathe in the summer.

The city's great vernacular statement-its guiding principle-is the row house. The balconied townhouse is to Montreal what the semi-detached Victorian is to Toronto, what the limestone apartment is to Paris. The row house falls somewhere between the two, merging the low height of Toronto's houses with the high population density of Paris's apartments.

From the industrial housing of Saint-Henri, through the elegant townhouses of the Plateau, to the duplexes of Little Italy, Montreal's residential neighbourhoods share a largely unbroken residential streetwall. Set-backs are just deep enough and roofs are just low enough to allow greenery to assert itself over the sidewalk. Montreal's neighbourhoods balance the density necessary for vibrant street life with the space necessary for a healthy sense of home.

Many of the historic neighbourhoods across North America have been razed to the ground. Fortunately, Montreal's characteristic communities have been preserved through a combination of luck, grassroots activism and respect for the character of the city. These neighbourhoods are the ground from which all future development in Montreal must be considered.

Montreal's experiments with urban development began in the 1950s and accelerated throughout the Jean Drapeau decades of the 1960s and 1970s. Alliances of developers, investors, planners and politicians-what academics Annick Germain and Damaris Rose call "urban growth machines"-were unleashed on the city in an attempt to modernize it into the mayor's grand vision of a global capital.

It was mayor Drapeau's mega-projects-the metro, the underground city-that left Montreal's residential neighbourhoods largely intact. In the downtown core, Dorchester (now René Lévesque) became the focal point of construction. Though new development radiated out from this grand, if inconsistent, boulevard, the impact of expansion beyond Dorchester was mediated by the existing scale of the city. Even on busy Sherbrooke Street, historic houses miraculously asserted their character over massive architectural interventions.

During Drapeau's leadership, commentators criticized the mayor's lack of a city-wide plan. But it is in part this absence of a cohesive urban vision that preserved Montreal's neighbourhoods. In Toronto, tracts of historic housing were demolished and replaced by stand-alone international-style apartment buildings in alienating, indefinable open spaces. In Paris, intensification of the city centre was rejected all together. Both approaches to planning produced overwhelmingly negative results. Toronto is divided into neighbourhoods and blocks where the city's urban character either lives among Victorian homes or dies on the senseless plains between street and tower. In Paris, the original arrondissements are little more than a series of postcards: corner cafes and consistent vanishing points as conceived two centuries ago by Haussmann.

In Montreal, the aptly named LaCité project is the most famous and, in many ways, illuminating residential development of Drapeau's period. LaCité was originally intended as a sixteen-building complex to encompass the four blocks at the intersection of Prince Arthur Street and Parc Avenue. But when local residents organized against the destruction of the site's poorly maintained (though elegant) townhouses, only three buildings were erected.

Despite a monumentally ugly design, LaCité as executed came to serve as a template for understanding high-rise development throughout the city centre. Apartment buildings spring upward from the streetwall, allowing the horizontal axis of the row houses to compensate for the sudden vertical thrust of tall intervention. Every building and every inhabitant stands on the same unbroken line, ensuring a consistent flow of neighbourhood traffic.

In the contemporary period, Montreal has not experienced the great wave of downtown high-rise condo-development currently underway in Toronto. No doubt this is because this city is not growing as quickly as Canada's financial capital, but it is also a reflection of how effective Montreal's row-house-lined neighbourhoods have been at absorbing the city's growth to date.

Montreal's streets possess a natural harmony missing in many modern cities. When architect Jack Diamond lay the apartment building on its side in the mid-1970s-the Sherbourne lanes project-he was commended for creating a friendlier residential strip in the midst of Toronto's poorly considered urban development. Yet this construction-which avoided isolated blocks and buildings interrupted by vague open spaces-achieved precisely what Montreal has already accomplished on nearly every residential street in the city centre.

The row house template need not be inherently conservative, either. Perhaps Moshe Safdie's Habitat, a functional relic of Expo '67, is the best example of how the row house can serve as a point of departure for, rather than exclude, more ambitious architectural forms. Safdie's long, low stacks of apartments serve as a deconstruction of the row-house-not so much a laying down of a tall building, but a twisting apart of a characteristic Montreal block.

Today Montreal continues to preserve the livable city. Throughout the industrial Mile-End, east of Saint-Laurent, there are now numerous new housing developments, contemporary riffs on the row house which re-stitch the streetwall rather than breaking it. The price of new architecture in Canada's most culturally vibrant metropolis cannot be the naturally evolving neighbourhood.