Nanteos is a large mansion built in the English Palladian style in 1739-57 and extended and otherwise altered in the earlier to mid nineteenth century. The house is thought to incorporate some fabric of an earlier house, presumably that mentioned in 1666. It features fourteen rather earlier slightly baroque windows thought to be reused from another house. The interior includes some outstanding original and nineteenth century features. The house stands at the centre of a great expance of parkland, grounds and gardens (NPRN 265018), entered from the west by a lodge (NPRN 279) and featuring a kennels-as-eyecatcher (NPRN 31525).

The original house is a three storey building with a principal seven bay south elevation, five bay return elevations and an irregular rear. It is built of local rubble stone with sandstone dressings under a continuous plain parapet punctuated by urns. The roofs are very low pitched or flat . In the main facade the centre three bays are distinguished by the use of dressed stone rather than rubble, and arched or round, rather than square-headed openings. The low four column portico or porch was added in 1848.
The sympathetic two storey east range was added in 1841 with a service range to the north. The single storey billiard room was added to the east range in 1862-7.

There is an impressive coachhouse and stable court to the north-east (NPRN 280) and a circular dovecote to the north (NPRN 31524). The remains of extensive walled gardens lie beyond the stable court.

A tradition has it that Nanteos was, until comparatively recently, home to the Holy Grail.

In 1863 Colonel Powell of Nanteos donated a plot of land for St Mary's Church, Aberystwyth (NPRN 306590), established to serve Welsh-speaking members of the established church.

Sources include:
Cadw, Listed Buildings Database

RCAHMW, February 2011