Columbia subject headings:
Cities and towns, Medieval--Europe.
Cities and towns--Europe--History.
Rhine River Valley--History.
Harvard subject headings:
Bonn (Germany)--History.
Cities and towns--Europe--History
Europe--History, Local.
Rhine River Valley--History
Princeton subject headings:
Bonn (Germany)--History.
Cities and towns--Europe--History.
Europe--History, Local.
Rhine River Valley--History.