Complex sentence: A street sign for Little Compton Street remains visible on a wall of a ultiity tunnel beneath a street grate on a traffic island in the middle of the junction of Old Compton Street and Charing Cross Road.
Split into simpler sentences: A street sign for Little Compton Street remains visible on a wall that is now subterranean. It can be seen through a street grate on a traffic island in the middle of the junction of Old Compton Street and Charing Cross Road.