This chapter introduces a series of examples of the unintended consequences, employing the insights of an unorthodox economist, Thomas C. Schelling, about how individual actions and decisions can lead to unintended and undesirable results on a large scale. The city will be shown to be full of silent chains of implications similar to the collective phenomena examined by Schelling. Armed with the initial analysis of contextual particularities in the city of Rio de Janeiro, the chapter looks more closely at the relationships between architecture, pedestrian movement and the materialisation of microeconomic activities in different architectural contextures. It examines properties most commonly associated with the vitality of local microeconomies. Building height, building density (floor area ratio) and density of economic units (units of residential and commercial activities per metre) also appear with positive correlations with pedestrians and to a lesser extent, commercial activities.