Blavia castellum was a military fort built by the Romans in the Aquitanian period of the Tractatus Armoricani especially Brittany .
The Tractatus Armoricani is an ancient and literary name for the northwest part of France .
Blavia castellum was a military fort built by the Romans in the Aquitanian period of the Tractatus Armoricani , an ancient and literary name for the northwest part of France , especially Brittany .