Columbia subject headings:
Harvard subject headings:
Castles--Austria--Lower Austria--History.
Lower Austria (Austria)--Antiquities.
Lower Austria (Austria)--Buildings, structures, etc.
Princeton subject headings:
Archaeology, Medieval--Austria--Lower Austria.
Castles--Austria--Lower Austria--History.
Excavations (Archaeology)--Austria--Lower Austria.
Lower Austria (Austria)--Antiquities.
Lower Austria (Austria)--Buildings, structures, etc.