Newton House (National Trust), Dinefwr Park

Dinefwr Park has a history of occupation spanning at least two millennia. A polished stone axe dated to the Neolithic period was unearthed on the site in 1976, and during the Iron Age, a farm existed on the property. The Romans later built a pair of forts here, with one partly overlying the other. There are traces of Roman roads and tracks, some of which may have been part of the Carmarthen–Llandovery Roman road. A Roman milestone and a Roman coin hoard were unearthed near Dinefwr Castle, and pieces of amphorae and Samian items have been excavated near Dinefwr Farm.

During the 12th century, Dinefwr Castle was built by Rhys ap Gruffydd, Prince of Wales. The castle and grounds were seized by Henry VIII in 1531, and the estate owners, who changed their family surname to Rice, subsequently had to buy back their property from the Crown. The family were elevated to the peerage of Great Britain as Baron Dynevor. Mary I is documented to have restored some of the land back to the Rhys family, but it was not until the reign of Charles I that the family fully regained their properties.

Newton House was originally built during the medieval period at some distance from the castle. It is documented to have been later modified in 1595 and 1603. The current Newton House was completed in 1660 under the command of Edward Rice. In the late 1700s, George Rice and his wife Cecil began the construction of a landscape garden, and hired eminent architect Capability Brown in 1775 to assume responsibility for the development. Turrets and battlements were added between 1760 and 1780, giving the property a more romanticised appearance.