Defended promontory. Earthwork remains survive on a raised rocky triangular promontory on south side of the narrow channel between St Michael's Isle and Langness.


The interior is surrounded by a bank except for a 20m strip to the south east. A pathway to the entrance is grooved with shallow steps cut into a natural shelf in the rock. This may also have served as a slipway for small boats. The entrance takes the form of a scooped hollow through the bank, 4m wide at the base and 9m wide across the top. The scooping of the entrance continues well into the interior of the fort.


The strength of the perimeter bank is variable, in some places surviving to maximal widths of 4 to 6m and heights of 1.1 to 1.6m above the interior. Elsewhere it is weaker and more fragmentary with an average width of 1.5m and an average height of 0.4m. No outer ditch is necessary and there is no visible trace of internal structures.


Limited excavation in 2000 recovered gorse charcoal dated to the 11th and 13th centuries. This may represent the firepit of a beacon serving as part of a watch and ward system of coastal defence.