Columbia subject headings:
City walls--Europe.
City walls--Italy.
Military architecture--Europe.
Military architecture--Italy.
Harvard subject headings:
City walls--Albania--Catalogs.
City walls--Conservation and restoration--Albania.
City walls--Conservation and restoration--Italy.
City walls--Conservation and restoration--Malta.
City walls--Conservation and restoration--San Marino.
City walls--Conservation and restoration--Vatican City.
City walls--Italy--Catalogs.
City walls--Malta--Catalogs.
City walls--San Marino--Catalogs.
City walls--Vatican City--Catalogs.
Princeton subject headings:
City walls--Europe.
City walls--Italy.
Military architecture--Europe.
Military architecture--Italy.