A complex earthwork castle occupying a steep-sided narrow promontory above the confluence of the Arth and Erthig streams.
The castle covers an area of some 90m east-west by at most 24m and opens onto a small plain fringed by wooded slopes on the east. The entrance negotiates a swathe of double ramparts and ditches set across the neck of the promontory, the inner rampart rising some 7.2m from the base of its ditch.

There are two adjacent steep-sided flat-topped mounds on the north side of the promontory. The first faces the entrance across a ditch. It is 7.2m high and some 30m in diameter, with a near rectangular summit some 10m across, presumably the site of a tower. The second mound is rather smaller, some 5.4m high, and lacks a ditch, but is otherwise similar and presumably also supported a tower. The remainder of the earthworks comprise a series of ledges, or platforms about the south side of the mounds. These are probably the site of the buildings of the castle court, including a hall.

The site is identified with a documented castle, first recorded (as destroyed) in 1137, whose demise is noted in 1207-8.

John Wiles, RCAHMW, 3 October 2007