The first time man made the world he made it by walking. The pathways people traveled wore out and became the primal architectural interventions in the landscape. These were the first delineations of the urban, of public space.
In Buenos Aires, by law, the sidewalks are to be maintained by the inhabitants of the adjacent buildings. Some areas have all tiles broken. People are forced to let their heads hang, staring at their feet, avoiding to trip or worse.