The defended settlement at Byrllysg is a rather oval enclosure, about 58m north-south by 54m, occupying the nub-end of an inland promontory, defined by scarps on the north, west & south, where the ground falls steeply away, with a bank and ditch facing relatively level ground on the east.

Source: Bowen & Gresham 1967 'Hist. Merioneth. I', 155.

J.Wiles 27.01.05