REMOVE

1. scaffolds
2. railroads
3. fences
4. bridges (built works)
5. black-and-white film

WHAT

1. Visual Works (hierarchy n … (1)
2. artists (visual artists) (1)
3. barriers (1)
4. benches (furniture) (1)

More 

WHERE

1. New York, New York (1)

WHO

1. Diane Still Knox; Diane K … (1)
2. Knox, Diane Still (1)

WHEN

1. 1958 (1)