Columbia subject headings:
Architecture, Medieval--Italy, Southern.
Fortification--Italy, Southern.
Frederick II, Holy Roman Emperor, 1194-1250.
Harvard subject headings:
Architecture, Medieval--Italy, Southern.
Castles--Italy, Southern.
Fortification--Italy, Southern.
Frederick II, Holy Roman Emperor, 1194-1250.
Italy, Southern--Buildings, structures, etc.
Princeton subject headings:
Architecture, Medieval--Italy, Southern.
Fortification--Italy, Southern.
Frederick II, Holy Roman Emperor, 1194-1250.