There is a patch of forest known colloquially as the “Tweed Woods” in the suburbs north of NYC. In these woods is a series of walls winding through its width. The walls are actually a tunnel system build by the US army in 1909. The land was used as a shooting/training range and the tunnels provided safe passage. The operation was shut down a few years later due to the hazards that flying bullets present to nearby farmers flesh. Abandoned walls (tunnels) will always attract the vibrant colors of graffiti even as nature reclaims those walls. Nature always wins.