Columbia subject headings:
Architecture, Medieval--Spain--Asturias.
Asturias (Spain)--Buildings, structures, etc.
Asturias (Spain)--History.
Towers--Spain--Asturias.
Harvard subject headings:
Asturias (Spain)--History
Towers--Spain--Asturias.
Princeton subject headings:
Architecture, Medieval--Spain--Asturias.
Fortification--Spain--Asturias.
Towers--Spain--Asturias.