Columbia subject headings:
Church architecture--Italy--Orvieto--History.
Duomo di Orvieto (Orvieto, Italy)--History.
Orvieto (Italy)--Church history.
Harvard subject headings:
Church architecture--Italy--Orvieto.
Duomo di Orvieto (Orvieto, Italy)
Orvieto (Italy)--Buildings, structures, etc.
Princeton subject headings:
Church architecture--Italy--Orvieto--History.
Duomo di Orvieto (Orvieto, Italy)--History.
Orvieto (Italy)--Church history.