Columbia subject headings:
Architecture--Germany--Cologne--History--21st century--Designs and plans.
City planning--Germany--Cologne--History--20th century.
City planning--Germany--Cologne--History--21st century.
Harvard subject headings:
Architecture--Germany--Cologne--21st century--Designs and plans.
City planning--Germany--Cologne--History--20th century.
City planning--Germany--Cologne--History--21st century.
Princeton subject headings: