Marked on the 1891 OS map, and still roofed on the 1901 map. Evidently an outbuilding of Gorllwyn Isaf farm as the maps show a track leading directly to it from the farmstead. Sited on a natural terrace and the outline of the building is defined by banks and boulder footings, with the N side apparently open. It measures 5.5m square.
Recorded as part of RCAHMW Uplands Initiative Project, W B Horton, H & H, 14/05/2013.