Walking is about being outside, in public space, and public space is also being abandoned and eroded in older cities, eclipsed by technologies and services that don’t require leaving home, and shadowed by fear in many places (and strange places are always more frightening than known ones, so the less one wanders the city the more alarming it seems, while the fewer the wanderers the more lonely and dangerous it really becomes). Meanwhile, in many new places, public space isn’t even in the design: what was once public space is designed to accommodate the privacy of automobiles; malls replace main streets; streets have no sidewalks; buildings are entered through their garages; city halls have no plazas; and everything has walls, bars, gates. Fear has created a whole style of architecture…In some places it is no longer possible to be out in public.
Rebecca Solnit, from Wanderlust: A History of Walking