Columbia subject headings:
Leaning Tower (Pisa, Italy)
Pisa (Italy)--Buildings, structures, etc.
Harvard subject headings:
Leaning Tower (Pisa, Italy)--Pictorial works.
Pisa (Italy)--Buildings, structures, etc.
Princeton subject headings:
Leaning Tower (Pisa, Italy)
Pisa (Italy)--Buildings, structures, etc.