Columbia subject headings:
Harvard subject headings:
Architecture--Italy--Siena--Sources.
Building--Italy--Siena--To 1500.
Cathedrals--Italy--Siena--Design and construction--History--To 1500.
Church architecture--Italy--Siena--Sources.
Duomo di Siena--History.
Duomo di Siena.
Opera della Metropolitana di Siena--History.
Opera della Metropolitana di Siena.
Siena (Italy)--Buildings, structures, etc.
Princeton subject headings:
Building--Italy--Siena--History--To 1500.
Cathedrals--Italy--Siena--Design and construction--History--to 1500.
Duomo di Siena--History.
Opera della Metropolitana di Siena--History.
Siena (Italy)--Buildings, structures, etc.