REMOVE

1. trees
2. rubbish
3. plants
4. sky
5. yards (areas)
6. artists (visual artists)

WHAT

1. Visual Works (hierarchy n … (1)
2. black-and-white film (1)
3. buildings (structures) (1)
4. bushes (1)

More 

WHERE

1. Westminster, Maryland (1)

WHEN

1. 1961 (1)
2. after 1961 (1)