Columbia subject headings:
Architecture, Medieval.
Building--Europe--History--To 1500.
Harvard subject headings:
Architecture, Medieval
Building--Europe--History--To 1500.
Building--Europe--To 1500.
Cathedrals--Europe--Design and construction--History.
Engineering--Europe--History--To 1500.
Princeton subject headings:
Architecture, Medieval.
Buildings--Europe--History.
Engineering--Europe--History.