Columbia subject headings:
Architecture, Medieval--Spain--Avila.
Avila (Spain)--Buildings, structures, etc.
City walls--Spain--Avila.
Harvard subject headings:
Architecture, Medieval--Spain--Avila.
Avila (Spain)--Buildings, structures, etc.
City walls--Spain--Avila.
Princeton subject headings:
Architecture, Medieval--Spain--Avila.
Avila (Spain)--Buildings, structures, etc.
City walls--Spain--Avila.