Columbia subject headings:
Dwellings--Italy--Rome.
Fortification--Italy--Rome.
Rome (Italy)--Buildings, structures, etc.
Towers--Italy--Rome.
Harvard subject headings:
Fortification--Italy--Rome.
Rome (Italy)--Buildings, structures, etc.
Towers--Italy--Rome.
Princeton subject headings:
Dwellings--Italy--Rome.
Fortification--Italy--Rome.
Rome (Italy)--Buildings, structures, etc.
Towers--Italy--Rome.