Columbia subject headings:
Architecture, Medieval--Pyrenees--Congresses.
Castles--Pyrenees--Congresses.
Fortification--Pyrenees--Congresses.
Military architecture--Pyrenees--History--Congresses.
Pyrenees--History, Military--Congresses.
Harvard subject headings:
Archaeology--Pyrenees--Congresses.
Fortification--Pyrenees--Congresses.
Fortification--Pyrenees--Exhibitions.
Princeton subject headings:
Fortification--Pyrenees--Exhibitions.