Columbia subject headings:
Architecture, Medieval--Italy--Rome.
Castles--Italy--Rome--Pictorial works.
Rome (Italy)--Buildings, structures, etc.
Suburbs--Italy--Rome--Pictorial works.
Towers--Italy--Rome--Pictorial works.
Harvard subject headings:
Castles--Italy--Rome (Province)--Guidebooks.
Castles--Italy--Rome--Guidebooks.
Rome (Italy : Province)--Guidebooks.
Rome (Italy)--Guidebooks.
Towers--Italy--Rome (Province)--Guidebooks.
Towers--Italy--Rome--Guidebooks.
Princeton subject headings:
Architecture, Medieval--Italy--Rome.
Castles--Italy--Rome.
Rome (Italy)--Buildings, structures, etc.
Towers--Italy--Rome.