Columbia subject headings:
Fortification--Spain--Navarre--Congresses.
Navarre (Spain)--History--Congresses.
Harvard subject headings:
Fortification--Spain--Pamplona.
Military architecture--Spain--Pamplona.
Pamplona (Spain)--Buildings, structures, etc.
Princeton subject headings:
Fortification--Spain--Navarre--Congresses.
Navarre (Spain)--History--Congresses.