17th century architecture Argolis battlements castle defence defense elements fort fortress Greece historical landmark Morea nafplio old Palamidi Peloponnese power ramparts stone stronghold venetian walls arch hill hilltop Remains ruins above ancient attraction cliff distant England fields headland keep monument ruin ruined rural scarborough tourist tower trees decay desuetude Greek high Mystras UNESCO World Heritage view wall window archway Asia china construct construction garrison Great Wall protect protection slope steep tourist attraction tree walk walkway wonder