Columbia subject headings:
Architecture, Medieval--Italy--Enna (Province)
Castles--Italy--Enna (Province)
Fortification--Italy--Enna (Province)
Harvard subject headings:
Architecture, Medieval--Italy--Enna (Province)
Castles--Italy--Enna (Province)
Fortification--Italy--Enna (Province)
Princeton subject headings:
Architecture, Medieval--Italy--Enna (Province).
Castles--Italy--Enna (Province).