The size of buildings will often define a city, for example in terms of their height and their ground footprint. Cities with many small low buildings will feel, and operate in a very different way to those with far fewer, larger taller buildings.

London is characterised by 2-3 storey streets and relatively small buildings other than in specific areas, such as its two financial centres , in the City of London and Canary Wharf.  than in specific areas such as the dsmallolder smaller the age ofamount of old buildthe richness, and diversity, in age and form of its building stock; from its elegant Georgian squares and adaptable Victorian terraces, to its imposing religious and industrial heritage, iconic modern commercial buildings, and vibrant streets of small shops.

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The size, shape and geometry of a city's buildings, and the way in which a city's buildings are packed together, will also affect how efficiently it operates, and the ease with which greenhouse gas emissions, pollution and the build-up of urban heat can be controlled. Data on these characteristics are also relevant to many other areas of urban research, from predicting housing capacity and identifying areas suitable for densification, to observing (within urban science and urban morphology) long-term patterns of change within urban form.