The castle mound at Castell Glas is flat-topped and trapezoidal, measuring overall 33m (north-east to southwest) by 25m on the north-east and 20m on the southwest. It has a maximum height of 1.8m on the south-east but only 0.6m on the north-west. The mound is turf-covered though probing suggests that it contains significant amounts of stone. It is now set in a children's playground.

RCAHMW, 2006