Pen-yr-Allt is a three-storey seventeenth century farmhouse which despite later alterations and additions still retains much of its external character. The south front is constructed of stone rubble with gable parapets and it has a slate roof and later brick stacks. There is a boarded door offset to the far right and to the left, there are two casement windows to each floor. To the right, there is also a lower two storey extension constructed of stone rubble with a slate roof. The inside of the house is said to contain chamfered beams and joists and a good inglenook fireplace with a curved bressumer over.

Source:- Cadw listed buildings, NJR 29/04/2008