Columbia subject headings:
Architecture, Medieval--Rhine River Valley--Congresses.
Art and history--Rhine River Valley--Congresses.
Art, Medieval--Rhine River Valley--Congresses.
Rhine River Valley--Civilization--Congresses.
Rhine River Valley--History--Congresses.
Harvard subject headings:
Architecture, Medieval--Rhine River Valley.
Art and history--Rhine River Valley.
Art, Medieval--Rhine River Valley.
Rhine River Valley--Civilization.
Rhine River Valley--History
Princeton subject headings:
Architecture, Medieval--Rhine River Valley--Congresses.
Art and history--Rhine River Valley--Congresses.
Art, Medieval--Rhine River Valley--Congresses.
Rhine River Valley--Civilization--Congresses.
Rhine River Valley--History--Congresses.