Things change. I have been in Larkspur, CA (right next to San Quentin) and saw the area where Dirty Harry jumps onto the school bus and then tracks down Scorpio ("....well, do ya, ..Punk?") . The trestle he jumped from is still there, but the area over the street is gone because a truck hit it in the past. The quarry he was chasing Scorpio around is now apartments, condos, and townhouses.