Its origins are older but the present building was constructed by the Monmouth architect George Vaughan Maddox for himself in 1834–1837, and subsequently altered by him after a later sale.

[2] Maddox, from a family of architects, had a significant practice in Monmouthshire and his works in Monmouth gave the county town, "its particular architectural flavour".

[3] Maddox certainly undertook works at Pentwyn on his own behalf, and Bradney suggests he designed further improvements after selling the property to the Reverend Canon John Harding in 1864.

These show scenic paths and a carriage drive, a kitchen garden, a conservatory and two areas of flat ground which were probably the sites for a tennis court and a croquet lawn.

The building is Grade II* listed, on account of its architectural interest and its historic connections with George Vaughan Maddox.