The monument comprises the remains of a defended enclosure, which probably dates to the Iron Age period (c. 800 BC - AD 74, the Roman conquest of Wales). It comprises two conjoined sub circular enclosures which together with an annexe occupy a blunt promontory above Martin’s Haven and the cove of Pwllcrochan in the tidal section of Milford Haven. An enclosure of c. 45m in diameter and D-shaped sits above the naturally steep east and south east promontory sides, a bank and ditch defend the north and west sides. Abutted to it on the north is a second enclosure measuring 70m north-south by 68m east to west, also banked and ditched except where resting on the steep east slopes. From the south west side of the first enclosure a third rampart extends north across the promontory to enclose an annexe of measurements c 175m north to south by c 150m east to west. A section cut through the annexe rampart revealed it to be 6m wide and 0.4m high and the ditch 3.6m wide and over 2m deep.