Columbia subject headings:
Architecture, Romanesque--Conservation and restoration--Italy--Ravenna.
Church architecture--Conservation and restoration--Italy--Ravenna.
Ravenna (Italy)--Buildings, structures, etc.
Harvard subject headings:
Architecture, Romanesque--Conservation and restoration--Italy--Ravenna.
Church architecture--Conservation and restoration--Italy--Ravenna.
Ravenna (Italy)--Buildings, structures, etc.
Princeton subject headings: