Columbia subject headings:
Fortification--Spain--Galicia (Region)
Galicia (Spain : Region)--History, Military.
Harvard subject headings:
Fortification--Spain--Galicia (Region)
Galicia (Spain : Region)--History, Military.
Princeton subject headings:
Castles--Spain--Galicia.
Fortification--Spain--Galicia.
Galicia (Spain : Region)--Description and travel.