Columbia subject headings:
Harvard subject headings:
Castles--Remodeling for other use--Europe.
Cultural property--Protection--Europe.
Fortification--Conservation and restoration--Europe.
Historic sites--Conservation and restoration--Europe.
Princeton subject headings:
Castles--Remodeling for other use--Europe.
Cultural property--Protection--Europe.
Fortification--Conservation and restoration--Europe.
Historic sites--Conservation and restoration--Europe.