Columbia subject headings:
Architecture--Germany--Frankfurt am Main.
Frankfurt am Main (Germany)--Buildings, structures, etc.
Harvard subject headings:
Architecture--Germany--Frankfurt am Main--History.
Frankfurt am Main (Germany)--Buildings, structures, etc.
Frankfurt am Main (Germany)--History
Historic sites--Germany--Frankfurt am Main.
Princeton subject headings:
Architecture--Germany--Frankfurt am Main.
Frankfurt am Main (Germany)--Buildings, structures, etc.