Columbia subject headings:
Harvard subject headings:
Architecture--Conservation and restoration--History--20th century--Congresses.
Historic buildings--Conservation and restoration--Congresses.
Historic preservation--Europe--History--Congresses.
Monuments--Conservation and restoration--Europe--History--Congresses.
World Heritage areas--History--Congresses.
Princeton subject headings:
Architecture--Conservation and restoration--History--20th century--Congresses.
Historic buildings--Conservation and restoration--Congresses.
Historic preservation--Europe--History--Congresses.
Monuments--Conservation and restoration--Europe--History--Congresses.
World Heritage areas--History--Congresses.