Columbia subject headings:
Architecture--Italy--Siena--History--21st century.
Siena (Italy)--Buildings, structures, etc.
Harvard subject headings:
Architecture--Italy--Siena--21st century.
Siena (Italy)--Buildings, structures, etc.
Princeton subject headings:
Architecture--Italy--Siena--History--21st century.
Siena (Italy)--Buildings, structures, etc.