Tall boundary wall across the back of Monk Haven beach, the date and purpose unknown, but said to be associated with the Trewarren estate, and therefore post 1845. It is constructed from red rubble sandstone, with rubble battlements and the outer third of each wall is stepped up and also battlemented. The wall may have originally been continuous with a door in the centre, but now has a full-height opening.The stonework seems to match that on the folly tower East of the bay.
It is included as a picturesque screen wall, a significant feature of Monk Haven and a part of the Trewarren estate.