Complex sentence: Bethesda Terrace is on two levels, united by two grand staircases and a lesser one that passes under Terrace Drive to provide passage southward to the Elkan Naumburg bandshell and The Mall at the center of the park.
Split into simpler sentences: Bethesda Terrace is on two levels, united by two grand staircases and a lesser one that passes under Terrace Drive. They provide passage southward to the Elkan Naumburg bandshell and The Mall at the center of the park.