A former movie palace in Southwest Philadelphia is poised to become a city landmark. A committee of the Philadelphia Historical Commission has approved a nomination to add the Ambassador Theatre in Cobbs Creek to the Philadelphia Register of Historic Places. The full commission is expected to take a second and final vote on the nomination during its next meeting on Aug. 14. Philadelphia once had more than 400 movie theaters. Every neighborhood in the city had at least one, and sometimes several, movie theaters at key commercial intersections,” said committee member Bruce Laverty during Wednesday’s meeting.