Alexander Chen took Massimo Vignelli's iconic 1972 map of the New York City subway system and turned it into a musical instrument. The routes are treated like strings, and whenever a train intersects a string, that string is plucked:
Length determines pitch, with longer strings playing lower notes. When a string is in the middle of being drawn by a subway car, its pitch is continually shifting. The sounds are cello pizzicato from the wonderful freesound.org, a set recorded by corsica_s. A complete chromatic scale was too dissonant. Ultimately I settled on a simple major C scale but with the lowest note as a raised third E, which keeps it from ever feeling fully resolved.
Link via Kottke