An amazing graffiti project my friend DK turned me on to:
eRuv is a digital graffiti project installed along the route of the former Third Avenue elevated train line in lower Manhattan. The train line, dismantled in 1955, was more than just a means of transport; it was part of an important religious boundary – an eruv – for a Hasidic community on the old Lower East Side. Using semacodes, the former boundary is reconstructed and mapped back onto the space of the city. Pedestrians with camera phones can then access location-specific historical content linked through the semacodes. Or you can cheat and see the amazing archival photos here.