Columbia subject headings:
Archaeology, Medieval--Italy--Bologna (Province)--Congresses.
Archaeology, Medieval--Italy--Modena (Province)--Congresses.
Castles--Italy--Bologna (Province)--Congresses.
Castles--Italy--Modena (Province)--Congresses.
Cities and towns, Medieval--Italy--Bologna (Province)--Congresses.
Cities and towns, Medieval--Italy--Modena (Province)--Congresses.
Fortification--Italy--Bologna (Province)--Congresses.
Fortification--Italy--Modena (Province)--Congresses.
Harvard subject headings:
Bologna (Italy : Province)--History--Congresses.
Castles--Italy--Bologna (Province)--Congresses.
Castles--Italy--Modena (Province)--Congresses.
Fortification--Italy--Bologna (Province)--Congresses.
Fortification--Italy--Modena (Province)--Congresses.
Modena (Italy : Province)--History--Congresses.
Princeton subject headings: