“Graffiti Archaeology is a project devoted to the study of graffiti-covered walls as they change over time. The core of the project is a timelapse collage, made of photos of graffiti taken at the same location by many different photographers over a span of several years. Most of the photos are from San Francisco, over a timespan from the late 1990’s to the present.”
The interface is a little awkward, but the content is well worth it.