The shattered ruins of a castle and the earthworks of a walled borough crown the upper slopes of a dramatically isolated and abrupt hill rising from the Tywi floodplain. Roman material recovered from the hill hints at the existence of an earlier settlement.The castle (NPRN100682) was established in the earlier thirteenth century and the borough received its charter in 1281. By the mid fourteenth century there were thirty-four burgages within the walls and fourteenth in 'Briggestrete' without. A burgage was a houseplot with certain rights and duties attached. The borough had been abandoned by the seventeenth century.
The borough was enclosed by strong ramparts and a stone wall, now buried in the earthworks that girdle the summit. There were two gates. Inside, building platforms and street lines can be discerned.

Source: Rees & Caple CADW Guide to Dinefwr Castle & Dryslwyn Castle, revised edition (2007)

John Wiles, RCAHMW, 6 December 2007