Columbia subject headings:
Architecture, Early Christian--Italy--Ravenna.
Church architecture--Italy--Ravenna.
Mosaics, Early Christian--Italy--Ravenna.
Harvard subject headings:
Architecture, Early Christian--Italy--Ravenna.
Church architecture--Italy--Ravenna.
Mosaics, Early Christian--Italy--Ravenna.
Ravenna (Italy)--Antiquities.
Ravenna (Italy)--Buildings, structures, etc.
Princeton subject headings: