Brilley is a parish in the northwest of the county close to the Welsh Border.  It's location near the Border is evident in its name which contains elements of both Welsh and English.

2.8km Northeast of the church and just north of Cwmma Farm is situated a circular mound 27m at base and 5m in height. The mound is oval in shape and unusually even, with no flat top. Though damaged, the motte probably held a tower, as there is no room for anything else. Upon the wall on the counterscarp bank buried foundations of a chemise wall can be found. There is much loose stone on the site, some of which shows diagonal tooling.

The upper bailey contains buried foundations but is densely covered by trees and undergrowth. Other evidence has been destroyed by roads and ploughing

There still exists signs of substantial wet defences and a stream that runs through the ditch on the west could have made this a wet moat.