Architecture 101 : 7

7. Suburban buildings are freestanding objects in space. Urban buildings are often shapers of space.

When we create buildings today, we frequently focus our efforts on their shapes, with the shape of outdoor space a rather accidental leftover. These outdoor spaces, such as those typically found in suburbans, are negative spaces because the buildings aren't arranged to lend shape to the spaces in between.
Urban buildings, however, are often designed under the opposite assumptions: building shapes can be secondary to the shape of public space, to the extent that some urban buildings are almost literally "deformed" so that the plazas, courtyards, and squares that abut them may be given positive shape.

From 101 Things I learned in Architecture School by Matthew Frederick.