Tthe Lunacy Act, of 1845 resulted in the counties of Monmouth, Hereford, Brecon and Radnor building a Joint Lunatic Asylum here at Abergavenny 1847-52. It initially had twelve wards and 210 inmates. The right hand Infirmary wing was added in 1859-61. The Laundry block was added in 1861-75. These completed the design by architect Thomas Fulljames which was much more Gothic in style than the building is today. Considerable extensions were added in the 1880s, and this included the re-modelling of the main central elevation. The majority of the stone rear ranges date from 1881-83 including the Central Administration Block and the Epileptic Block. The Working Men's Dormitory was added in 1891 by Alfred Swash, and further work was done in 1901-4 and 1910, this involved the rebuilding of the four main gables and was done by the local architect Edward Johnson; subsequent ranges and alterations in conversion to modern hospital use.
During the latter half of 19th century the catchment area for this asylum was greatly reduced, although it could now house 1170 patients. It became the Monmouthshire Asylum in 1897, the Monmouth Mental Hospital in 1930 and finally Pen-y-Val Hospital in 1948. With changing attitudes to mental care the use of the hospital declined and it was closed in 1997. A scheme for conversion to apartments was drawn up by Graham Frecknall of Monmouth and this has now been fully realised. It has involved the demolition of certain sections of the hospital buildings described above, but the main long range with the return wings at either end has been carefully restored, as have the Lodge and all the Shelters in the gardens, the Church remains in need of repair and reuse. The projecting and clasping blocks at the south-east (Infirmary) and north-west ends of the main range survive only in part, while everything behind the main range apart from the two principal wings has gone and this includes the Central Administration Block and most of the additions of 1881-3 and of 1891 mentioned above. These have been replaced by new build, with two rows of houses in the rear centre as well as many new houses on the northern part of the site and two matching Lodges at the site entrance by the railway bridge, these last being in a deliberate repro-style.
Reference: Cadw listed buildings database.