Grotto in Gnoll Estate

Cadw's description

Location

At the NE end of the Gnoll Estate on the hillside immediately W of the informal cascade.

History

The extensive park and grounds at the Gnoll were laid out for Sir Humphrey Mackworth in 1724-7 and were centred upon fish ponds (that also supplied water to his copper works) and cascades. An informal upper cascade in Mosshouse Wood was added in the 1740s by an unknown designer, working for Herbert Mackworth. The grotto beside the cascade was also added at this time. Follies were later added in the 1780s by Sir Herbert Mackworth, which included a gazebo above the grotto and the Ivy Tower. The late C18 was the heyday of the Gnoll grounds, although it was revived in the C19 by the Grant family and Charles Evan Thomas. The latter came to an agreement with Neath Corporation for the building of Mosshouse Wood reservoir, which is dated 1889. The estate was acquired by the local authority in 1923. The house was demolished in 1957. Restoration of the grounds began in 1984-5 when the grotto was rediscovered.

Exterior

Cut into bedrock beneath a rebuilt gazebo. The entrance has a large bedrock lintel and is flanked by drystone revetment walls, the whole composition intended to resemble a Cotswold-Severn style prehistoric chamber tomb. Inside, the single circular chamber is quarried out of bedrock and has a crude flattened domical stone vault, which was intended to drip lime and form stalactites. The floor has an outer circular pavement of random paving stones and a kerb, which probably defines a former pool in the centre.

Reason for designation

Listed as an unusual and well-preserved feature of an important landscape garden, and for group value with the adjacent cascade.