New Urban News Technical Page by Andres Duany, Michael Morrissey, and Patrick Pinnell
Most urban open space, whether it is a plaza, square, or green, is detached from the surrounding blocks by a surrounding street. An attached open space is one that shares its urban block with one or more major buildings. According to William H. Whyte, from his empirical studies on urban behavior, the attached square (the type found at the midpoint of the urban-rural transect) is more likely to be used than one surrounded by traffic. Urban spaces are activated to a great extent by the life in the buildings at their edges, particularly if these buildings supply shopping, food, and drink. Whyte discovered that the most used attached squares were at the corner of a block, tapping into the diagonal pedestrian shortcut.