aerial view of walls and bastions of modern six-star hexagon d fort cittadella of alessandria on winding river tanaro

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 panorama piedmont plan ponte quarter ramparts regular river sardinia savoy shape shaped six square star tanaro towers town travel view walls winding