1. Llyswen Mill is a derelict, stone-built, water powered corn-mill with mill-pond and leet, fed from the Aeron River. It may date from the 17th century, or earlier but was probably rebuilt in the early-19th century. There had been a manorial court at Llyswen since the 13th century, which by 1693 had become part of the Monachty Estate. A reference to a mill is made by the court at Llyswen in 1693, stating that thatch should be provided for the ?Lord's Mill?. A land dispute between 1700 and 1709 first mentions the ?mill of Llyswen.
The surviving remains include the west gable-end, side-wall footings, projecting wing footings, water-wheel pit and mill race. The west gable-end has rounded corners and along with the north wall, both have thicker walls, indicating an earlier, possibly 17th century building. In c1926 it was converted to produce electricity for Aberaeron and soon extended by the addition, at the west gable-end, of a large iron-framed, corrugated-iron building. Later the Electricity Board took it over, until production of electricity ceased in the mid-1950s. At one time electricity was produced by two turbines with diesel generators. A further small brick building adjoining may have been added as a control room by the Electricity Board.
The corn-mill's west gable-end has a wide opening for cart access and a loading door above, which has been enlarged when the iron-framed building was added. This end wall retains evidence of an earlier, lower roof-line, perhaps relating to the thicker walls. Against the north wall are footings for a 19th century wing with a doorway opening in its west side. This is shown as a 2-storey wing in a c1900 photo, which also shows that the slate-roofed mill had an overshot water-wheel fed by a timber trough, from a stone banked mill pond .
Another photo of similar date shows a slate-roofed detached 2-storey stone building (now demolished) close to the north-west corner of the mill, probably a stable with east gable-end loading doorway to a hay loft over.
Reference. Jones,D.L., Aberaeron Before The Harbour Act of 1807 in Ceredigion, Vol 1X, 1983, Monachty Estate Records, NLW and the owner Mair Harrison.
The building was recorded, by Geoff Ward & J Davies, at the request of Mair Harrison & Olwen Jenkins due to its derelict condition.

2. The 1st and 2nd editions of the historic 25-inch O. S. maps, published in 1890 and 1905 respectively, annotate the mill as a working corn mill, driven by water abstracted at a weir on the Afon Aeron and conveyed along a carefully constructed mill race, 580 metres long, to a wheel on the mill's east gable. Much of the mill building shown on these maps had collapsed.
W J Crompton, RCAHMW, 6 December 2018.