Columbia subject headings:
Leaning Tower (Pisa, Italy)
Pisa (Italy)--Buildings, structures, etc.
Harvard subject headings:
Architecture--Conservation and restoration--Italy--Pisa.
Architecture--Italy--Pisa--Conservation and restoration.
Leaning Tower (Pisa, Italy)
Pisa (Italy)--Buildings, structures, etc.
Towers--Conservation and restoration--Italy--Pisa.
Princeton subject headings:
Architecture--Conservation and restoration--Italy--Pisa.
Leaning Tower (Pisa, Italy)