Columbia subject headings:
City walls--Germany--Cologne.
Cologne (Germany)--Antiquities, Roman.
Germany (West)--Antiquities, Roman.
Romans--Germany--Cologne.
Walls, Roman--Germany--Cologne.
Harvard subject headings:
Cologne (Germany)--Antiquities, Roman.
Germany (West)--Antiquities, Roman.
Romans--Germany (West)--Cologne.
Walls--Germany--Cologne.
Princeton subject headings:
City walls--Germany--Cologne.
Cologne (Germany)--Antiquities, Roman.
Cologne (Germany)--Buildings, structures, etc.
Germany--Antiquities, Roman.
Romans--Germany--Cologne.