New York City is a place of constant activity – indoors, outdoors, above ground and underground.  One of its most famous landmarks, the subway, is a thriving city under the surface – complete with a transient population, a constantly changing environment and an atmosphere of both rush and relief.  Riding the subways and observing its scraped off posters with remnants of visuals from past occupants of the wall spaces leaves you with an appreciation of the place and the people who use it.