Pen y Cnap Castle is known to be a motte, although the existence of a bailey is unproven. It is noted that, in 1203, Rhys Ieuanc, son of Rhys ap Gruffudd (the Lord Rhys) came into possession of the castle. The motte is situated some 250m west of St Egwad's Church (NPRN 309912).

The motte is a Scheduled Ancient Monument. Measurements are given as 5.6m height, 11m summit diameter. The track of the ditch can be traced and there are traces of stonework about the motte summit.

Sources include:
www.genuki.org.uk

N Vousden, RCAHMW, 22 January 2013