Possible Clues:

• Major Civil War battle site in Pennsylvania
• Art museum named for an oil magnate
• Battleground of 1863
• Scene of Lincoln's address
• Site of Lincoln's address
• Historic American address
• What bicentenarian said of museum man — 'citizen eating snake without its tail'
• See 62-Down
• Battle site gunners ignored aimless strategy by returning victuals
• Good painter works hard over place with famous address