Downtown is a 1990 American police action comedy film directed by Richard Benjamin.
Though the plot of the movie references a Philadelphia suburb, Bryn Mawr, most of the exterior filming is done within the City of Philadelphia. The beginning of the film features Cresheim Valley Road, Stenton, and Germantown Avenues. This is in the Mount Airy and Chestnut Hill neighborhoods. However, there are a few early scenes that are filmed in and around Los Angeles. For example, the scene where Anthony Edwards pretends to pull over Penelope Ann Miller is filmed on Yale Street, in Claremont, CA. Later portions of the film are in the Fairhill and Norris Square neighborhoods which are now known as The Badlands circa 2000. Diamond Street is within this area, but Philadelphia police districts are numbered, not named for streets or neighborhoods. Any Philadelphian would enjoy trying to catch their street in the fast paced filming.
Source: Wikipedia