Columbia subject headings:
Brochs.
Iron age--Scotland--Orkney.
Orkney (Scotland)--Antiquities.
Scotland--Antiquities.
Harvard subject headings:
Brochs.
Iron age--Scotland--Orkney.
Orkney (Scotland)--Antiquities.
Scotland--Antiquities.
Princeton subject headings:
Brochs.
Iron age--Scotland--Orkney.
Orkney (Scotland)--Antiquities.
Scotland--Antiquities.