Columbia subject headings:
Art, Italian.
Bologna (Italy)--Buildings, structures, etc.
Bologna (Italy)--History.
Towers in art.
Towers--Italy--Bologna.
Harvard subject headings:
Bologna (Italy)--Buildings, structures, etc.
Bologna (Italy)--History
Bologna (Italy)--In art.
Towers--Italy--Bologna.
Princeton subject headings:
Art, Italian.
Bologna (Italy)--Buildings, structures, etc.
Bologna (Italy)--History.
Towers in art.
Towers--Italy--Bologna.