There has been a house at Pantglas since medieval times, but the location and description of the original estate and buildings are lost. So we start in 1822, when the Pantglas Hall estate was sold to Jones &Co, founders of the Black Ox Bank of Llandovery, which was later incorporated into Lloyds.
The family re-built the house in the Italianate style that is still evident from the remaining tower. It cost some £30,000 to build and was described as ‘a house of considerable significance’. The entrances to the estate were protected by four gatehouses – Llandeilo, Carmarthen, Gardener's and North Lodge – all of which are still occupied and in private ownership today.
In 1922, the mansion was sold from private ownership to the local authority. Carmarthenshire County Council first used the house as a home for unmarried mothers, and then as a general mental health hospital, and at one time, there were over 140 patients registered at Pantglas Hall.
Although the main house accommodated most patients, there was also a large dormitory in the present function room of the mews building. The laundry was housed in what is now the games area, and there are tales that a hidden underground passageway led to the main house from this room. The coffee shop was used as workshops and the restaurant was an entertainment hall with dances for staff and residents often held there. The staff quarters were above the restaurant, although the Matron had the honour of a room in the big house.
A fire in 1968 caused considerable smoke damage to the mansion, and the house and grounds were sold to a private developer in 1972. The tower, mews building, bridge and walled garden are protected under Grade 2 listing, and many of the trees around the resort are also protected.