Columbia subject headings:
Harvard subject headings:
Architecture--Conservation and restoration--Spain--Congresses.
Cities and towns--Conservation and restoration--Spain--Congresses.
Historic buildings--Conservation and restoration--Spain--Congresses.
Monuments--Spain--Conservation and restoration--Congresses.
Spain--Antiquities--Congresses.
Stone buildings--Conservation and restoration--Spain--Congresses.
Weathering of buildings--Spain--Congresses.
Princeton subject headings:
Art--Conservation and restoration--Congresses.