Columbia subject headings:
Architecture, Medieval--Italy--History--Congresses.
Castles--Italy--History--To 1500--Congresses.
Cities and towns, Medieval--Italy--History--To 1500--Congresses.
Fortification--Italy--History--To 1500--Congresses.
Harvard subject headings:
Castles--Italy--Congresses.
Cities and towns, Medieval--Italy--Congresses.
Fortification--Italy--Congresses.
Princeton subject headings:
Castles--Italy--Congresses.
Cities and towns, Medieval--Italy--Congresses.
Fortification--Italy--Congresses.