Columbia subject headings:
Fortification--Austria--Vienna.
Vienna (Austria)--Buildings, structures, etc.
Vienna (Austria)--History.
Vienna (Austria)--Social life and customs.
Harvard subject headings:
Fortification--Austria--Vienna.
Vienna (Austria)--Buildings, structures, etc.
Vienna (Austria)--History.
Vienna (Austria)--Social life and customs.
Princeton subject headings:
Vienna (Austria)--History.