Columbia subject headings:
Architecture, Romanesque--Italy--Puglia.
Buildings, Octagonal--Italy--Puglia.
Castello del Monte (Italy)--History.
Frederick II, Holy Roman Emperor, 1194-1250--Homes and haunts--Italy--Puglia.
Harvard subject headings:
Architecture, Medieval--Italy--Puglia.
Buildings, Octagonal--Italy--Puglia.
Castello del Monte (Italy)
Castles--Italy--Puglia.
Princeton subject headings:
Castello del Monte (Italy)
Castles--Italy--Puglia.