REMOVE

1. hats
2. sky
3. trains (vehicle groupings)
4. freight cars

WHAT

1. Visual Works (hierarchy n … (1)
2. artists (visual artists) (1)
3. automobiles (1)
4. banks (landforms) (1)
5. barns (1)

More 

WHERE

1. Westminster, Maryland (1)

WHEN

1. 1965 (1)
2. 1966 (1)
3. ca. 1965 - 1966 (1)