Dinefwr is an iconic place in the history of Wales. It encompasses a National Nature Reserve, the 17th-century mansion of Newton House and its superb 18th-century landscape park. Newton House was built by Edward Rice in 1660-4 and was remodelled in 1770 by George Rice and his wife, Lady Cecil Talbot, who became the Baroness Dynevor in 1782. The Rices were largely responsible for designing the landscape. George Rice Trevor, the 4th Baron Dynevor, inherited the Dinefwr estate in 1852 and engaged the architect Richard Kyrke Penson to modernise the house. His neo-Jacobean and Gothic designs included encapsulating the house within a stone façade and adding four tower turrets. Newton House sits in the grounds of Dinefwr Castle which is today owned by the Wildlife Trust and operated by Cadw. The powerful Lord Rhys, ruler of the kingdom of Deheubarth from 1155 to 1197, held court here.