Many of the world's upcoming building projects are located in dense areas where structures of great height have already been established. This is especially true in the CBD, or central business district, of a particular city. These areas, often coiciding with the financial district, are where the municipality's primary business and commercial activities take place. 

Toronto's central business district, image by Marcus Mitanis

Though CBDs are often located within a downtown core or city centre, this is not always the case. Lower Manhattan is frequently called Downtown Manhattan although the world's largest CBD is situated within Midtown. London's Canary Wharf and Docklands area usually share the CBD title along with the traditional core of London and the City of Westminster. 

Canary Wharf in London, image by stevekeiretsu via Flickr

Although the CBD is typically home to the city's tallest buildings and most expensive land, resident populations are usually small since most activity is commercial in nature. As downtown living becomes more attractive in North American and Australian cities which have historically been marred by sprawling suburbs, new residential projects are now popping up in CBDs. 

La Défense, the main CBD of Paris, image by Zinneke via Wikimedia Commons