Columbia subject headings:
Castles--Italy--Marche.
Fortification--Italy--Marche.
Papal States--History--1605-1799.
Harvard subject headings:
Fortification--Italy--Marche.
Marche (Italy)--Defenses--History.
Marche (Italy)--Population--History.
Princeton subject headings:
Marche (Italy)--Defenses--History.
Marche (Italy)--Population--History.