Columbia subject headings:
Architecture, Domestic--Germany--Ruhr (Region)
Architecture--Germany--Ruhr (Region)--History--20th century.
Public architecture--Germany--Ruhr (Region)
Harvard subject headings:
Architecture--Germany--Essen--20th century.
Architecture--Germany--Ruhr River region--20th century.
City planning--Germany--Ruhr River region.
Regional planning--Germany
Princeton subject headings: