A sub-circular enclosure occupying a low spur projecting south-west from the lower slopes of Mynydd y Graig measures internally about 47m across and is defined by a bank, faced with stone, 1m high. Its location on elevated ground diminishing in height towards the neck of the spur (now occupied by a ruined farmhouse) suggests a defensive role for the enclosure before being given over to cultivation and a garden to the house. But there is no conclusive evidence pointing to a defensive function.

When approached from the south or south-west this location has the appearance of a well-defended position, approached via a bank about 4m high, the outermost scarp of the spur. The interior is a level, well-drained grassy area surrounded by a wall, in fact a stone-faced bank defining an irregular sub-oval or sub-circular enclosure. The north-east end, the neck of the spur, is occupied by the ruined farmhouse, Tyddyn-castell, by which the enclosure may originally have been entered. Externally, around the west and north-west, the bank (or scarp of the spur) remains prominent, 2m-3m high, diminishing only on the north as the house is approached. Around the south and east by contrast, the bank diminishes sharply to be replaced by a 1m-1.5m high wall-bank. Although the name suggests a defensive site there is no sign of a ditch or rampart. The present wall-bank gives the impression of a field or garden attached to the house.

David Leighton, RCAHMW, 24 July 2006