Columbia subject headings:
Art, Italian--Italy--Rome--Guidebooks.
Art--Italy--Rome--Guidebooks.
Museo nazionale di Castel Sant'Angelo--Guidebooks.
Rome (Italy)--Guidebooks.
Harvard subject headings:
Art, Italian--Italy--Rome--Guidebooks.
Art--Italy--Rome--Guidebooks.
Castles--Italy--Rome--Guidebooks.
Museo nazionale di Castel Sant'Angelo--Guidebooks.
Rome (Italy)--Buildings, structures, etc.--Guidebooks.
Rome (Italy)--Guidebooks.
Princeton subject headings: