Columbia subject headings:
Cathedrals--Italy--Siena.
Duomo di Siena.
Harvard subject headings:
Christian art and symbolism--Medieval, 500-1500--Italy--Siena.
Church decoration and ornament--Italy--Siena.
Duomo di Siena.
Siena (Italy)--Buildings, structures, etc.
Princeton subject headings:
Duomo di Siena.