Pastscape contains a detailed description. Summary:
The substantial earthworks of an Iron Age promontory fort known as Countisbury Castle, but more commonly referred to as Wind Hill, have been surveyed by field investigators at 1:2500 and transcribed from aerial photographs. The defensive earthworks, which comprise an east-facing bank and ditch with a broad low counterscarp bank, cross a saddle of land between sea cliffs to the north and the precipitous slopes of the East Lyn Valley on the south. The earthworks are broken by the modern route of the A39 and an original entrance, to the east of which extends an outworks. The southern end of the western rampart is abutted an extended westwards by a lynchet of probable medieval date.