Columbia subject headings:
Limes (Roman boundary)--Congresses.
Military history, Ancient--Congresses.
Harvard subject headings:
Classical antiquities--Congresses.
Fortification, Roman--Congresses.
Fortification, Roman.
Limes (Roman boundary)
Limes (Roman boundary)--Congresses.
Military history, Ancient--Congresses.
Rome--Antiquities--Congresses.
Rome--History, Military--Congresses.
Princeton subject headings: