Columbia subject headings:
Harvard subject headings:
Architecture, Domestic--Germany--History--Congresses.
Architecture, Medieval--Congresses
Castles--Germany--History--Congresses.
Castles--Remodeling for other use--Germany--History--Congresses.
Fortification--Germany--History--Congresses.
Princeton subject headings:
Architecture, Domestic--Germany--History--Congresses.
Architecture, Medieval--Congresses.
Castles--Germany--History--Congresses.
Castles--Remodeling for other use--Germany--History--Congresses.
Fortification--Germany--History--Congresses.