Several sources say that Ed Wood filmed Plan 9 from Outer Space at Quality Studios, the entranceway located next to the Harvey Hotel. The building is still there, though not a studio anymore. I've verified from old postcards that the large building used to be the Harvey Hotel.
Movie Locations, Studios
Plan 9 from Outer Space is often said to be the worst movie ever made. It was also Bela Lugosi's last film.