Plas Llanarmon is a gentry house of the 17th century, later a farmhouse. In the late 19th century it was tenanted by John Parry (1835-95) whose campaign against collection of tithes from tenants led to his eviction (cf Parry Memorial at Capel Bethel, Rhiw Ial).

The house is rubble stone, two storeys and attic with slate roofs. It has a short main range dominated by crosswings of unequal size, the smaller wing to the right forming a storeyed porch.

The south crosswing is said to have an important 17th century decorated plaster ceiling in panels with vine trail and floral trail motifs, in the centre a human figure with flowers. There is one plastered beam. In the crosswing is a stair hall with an oak dog-leg stair with turned balusters and square newels. The centre room has one heavy beam and deep fireplace to right.

Reference: Cadw listed buildings database.