Llanerchaeron

Llanerchaeron, pronunciation^ⓘ known as "Llanayron House" to its nineteenth-century occupants, is a grade I listed mansion on the River Aeron, designed and built in 1795 by John Nash for Major (later Colonel) William Lewis as a model self-sufficient farm complex located near Ciliau Aeron, some 2+1⁄2 miles south-east of Aberaeron, Ceredigion, Wales. There is evidence that the house replaced an earlier mansion. A later owner, William Lewes, was the husband of Colonel Lewis's inheriting daughter.

The estate is now in the care of the National Trust. The gardens and the parkland are listed on the Cadw/ICOMOS Register of Parks and Gardens of Special Historic Interest in Wales. The neighbouring parish church of St Non – also redesigned by Nash – has registers of baptisms and burials dating from 1730 and marriages from 1754.