aerial helicopter view of walls, moats, bastions, earthworks, outworks and barracks of six-star hexagon d renaissance fort

aerial alessandria architecture barracks bastions bridge buildings casemates citadel cittadella city ditches duchy earthworks empire europe fort fortification fortress italy kingdom landscape meier moats modern nature new old outworks panoramic piedmont plan ponte quarter ramparts regular renaissance sardinia savoy shape shaped six square star stone towers town travel view walls winding