The historic center of Ottawa, which includes the former Bytown, is located between the canal and the confluence of the Ottawa, Gatineau and Rideau rivers. Its borders are roughly Rideau Street, Sussex Drive, Byward Market near King Edward Street, and the Rideau River. This is traditionally the French-speaking area of town, though today Anglophones outnumber Francophones, and significant numbers of immigrants and ethnic minorities dwell here as well.

Downtown is the government, financial and commercial hub of the city. Parliament Hill is at the north edge of the city on a great bluff overlooking the Ottawa River; to the east and west are the major government buildings and museums, including the Supreme Court of Canada and the National Gallery; and to the south are the downtown highrises that consist of office towers and some apartments and condominiums.  Just east of parliament is the Byward Market, a lively district of restaurants, clubs, condos and apartments and shopping.

Just to the south of the downtown core is the neighbourhood of Centretown.  Roughly bounded by Gloucester Street to the north, the Rideau Canal to the east, Bronson Avenue to the west and the Queensway (Highway 417) to the south, this very urban community consists primarily of small apartment buildings and large homes (many of which have been converted to apartments), along with small stores, restaurants and bars along the major streets (Bank and Elgin).  Ottawa's "gay village" is located in centred on Bank Street south of Somerset.

Just beyond the downtown core are a number of popular neighbourhoods with strong residential communities and vibrant strips of shopping and restaurants.  To the south of the Queensway is the Glebe (bounded roughly by Queensway/Rideau Canal/Bronson), which in addition to shops and restaurants down its Bank Street core, includes Lansdowne Park (home of the Central Canada Exhibition each August, concerts and trade shows throughout the year and the Ottawa 67s junior hockey team in the winter).  In late May, the Glebe is inundated with bargain hunters as almost every home becomes a storefront during the "Great Glebe Garage Sale".  Further south is Old Ottawa South (bounded roughly by Rideau Canal/Rideau River/Bronson), which includes "Antiques Row" along its Bank Street commercial strip, and is the neighbourhood closest to Carleton University.

To the east just beyond the downtown core is Sandy Hill (bounded roughly by Rideau Canal/Rideau Street/Rideau River).  Home to the University of Ottawa, this old Ottawa neighbourhood consists of numerous large homes, some of which have been turned into student apartments, while others house stately embassys.  Further northeast of downtown, at the end of Sussex Drive is the beginning of Rockcliffe Park, Ottawa's most exclusive neighbourhood.  Numerous foreign countries own expansive properties here (including USA, UK, France, South Africa) for use as formal residences of their ambassadors during their Canadian postings.  On Sussex Drive on the edge of Rockcliffe you will also find the official residences of Canada's Prime Minister (24 Sussex Drive - closed to the public) and Canada's Governor General ( Rideau Hall - open to the public).

To the west, just beyond the downtown core, are four neighbourhoods of note.  Chinatown is a small strip centred on Somerset Street, beginning within Centretown at Lyon, continuing west to Preston Street.  Today, this diverse community not only sports very good Chinese food and shopping options, but also a vibrant Vietnamese community.  Preston Street itself is the backbone of Little Italy, with numerous Italian eating options.  Further west is the residential neighbourhood of Wellington West/Island Park, highlighted by a commercial strip along Wellington with numerous restaurants and furniture stores, and a series of embassys, particularly along Island Park Drive.  Just beyond Island Park is the up-and-coming neighbourhood of Westboro.  Popular for its shopping along Richmond Road, Westboro is particularly known for its stores devoted to outdoor adventure clothing and gear.  Richmond Road is closed for 3 days each June for Westboro's annual street festival, Westfest.

Beyond these central neighbourhoods is the expanse of the city of Ottawa, which was greatly expanded in 2000 through amalgamation with numerous suburban cities and rural townships.  Dividing the "near suburbs" and "far suburbs" is the greenbelt - a great swath of land encircling the city owned by the federal government.  While a few businesses operate within the greenbelt (e.g. Nortel's main Ottawa campus, the Ottawa Airport), most of this area is maintained as farmland.  There are also two communities of homes and businesses that continue to thrive within the greenbelt - Bell's Corners to the east, and Blackburn Hamlet to the west.

Suburban communities within the greenbelt include: Nepean, Centrepoint, Britannia, Leslie Park, Bayshore, Frank Ryan, Parkwood Hills, Riverside Park, Hunt Club, Alta Vista, Vanier, Manor Park, Overbrook and Carsons Glen.  Newer communities have sprouted beyond the greenbelt - these areas are connected to the main part of the city through highways, major throughfares and transitway routes - including: Kanata, Stittsville, Barrhaven, Riverside South, Orleans.  Beyond these neighborhoods also lies a significant urban fringe of satellite towns and rural communities such as Constance Bay, Kars, Metcalfe, Munster, Manotick, Osgoode, Richmond, Naven and Rockland. Most of these small cities usually have populations of less than three thousand.

On the Quebec side of Canada across the river lies the city of Gatineau. Also a result of recent amalgation, Gatineau consists primarily of its three former cities: Hull (directly across the river from Ottawa and home to the Museum of Civilization), Aylmer (to the west of Hull), and the original centre of Gatineau (to the northeast of Hull). Though a separate city, together with Ottawa it makes up the official National Capital Region, and public transportation services run between the two cities.