Columbia subject headings:
Fortification.
Leonardo, da Vinci, 1452-1519.
Military architecture.
Harvard subject headings:
Fortification--Italy--History.
Leonardo, da Vinci, 1452-1519
Military architecture--Designs and plans--Catalogs.
Princeton subject headings:
Fortification--Italy--History.
Leonardo, da Vinci, 1452-1519.
Military architecture--Designs and plans--Catalogs.