REMOVE

1. plants
2. backdrops
3. rivers
4. trees
5. buildings (structures)
6. black-and-white film
7. sitting

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)