Columbia subject headings:
Architecture--Spain--History--20th century.
Building, Iron and steel--Spain--History--20th century.
Building, Iron and steel--Spain--History--21st century.
Harvard subject headings:
Architecture--Spain--History--20th century
Building, Iron and steel--Spain--History--20th century.
Building, Iron and steel--Spain--History--21st century.
Princeton subject headings:
Architecture--Spain--History--20th century.
Building, Iron and steel--Spain--History--20th century.
Building, Iron and steel--Spain--History--21st century.