REMOVE

1. barriers
2. trees
3. stables (animal housing)

WHAT

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

More 

WHERE

1. Aiken, South Carolina (1)

WHO

1. Clyfford Still; Still, Cl … (1)
2. Still, Clyfford (1)

WHEN

1. 1966 (1)