Ключевые слова: aerial, aerial photography, aerial survey, air photography, ancient, architecture, bastion, castle, citadel, day, defense, defensive, deserted, donjon, drone, early, europe, finland, fortification, fortress, historical, history, island, july, lake, landmark, landscape, medieval, morning, northern, olafsborg, olavinlinna, old, reflection, saimaa, savonlinna, scandinavia, summer, sunny, three, top view, tower, travel, view, wall, water, water area, water surface,