Columbia subject headings:
Harvard subject headings:
Aqueducts--Germany--Cologne--History.
Aqueducts--Rome.
Cologne (Germany)--Antiquities, Roman.
Water-supply engineering--Germany--Cologne--History.
Water-supply engineering--Rome.
Princeton subject headings:
Aqueducts--Germany--Cologne--History.
Aqueducts--Rome.
Cologne (Germany)--Antiquities, Roman.
Water-supply engineering--Germany--Cologne--History.
Water-supply engineering--Rome.