Two rooms are open to the public, including a tearoom and exhibition in the basement and ground floor which contain numerous displays related to the history of the estate and occupants.

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.

[2][6] 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.

[7] During the Rebecca Riots of 1843, Colonel George Rice was awoken one night in September and found an empty grave dug in the grounds, warning him that he would be buried in it by October 10.

His son Charles Rhys, 8th Baron Dynevor, died just six years later, and most of the estate and a number of family's assets had to be sold off to pay duties.

[4] In 1974, the property was sold by Richard Rhys, 9th Baron Dynevor, and later fell into disrepair: it was occupied by squatters and thieves who removed beams and furniture.

[7] Though the property remains Jacobean, around 1856,[9] there were significant changes made in the Venetian Gothic style,[10] which today emanate the ambience of the Victorian period.

[11] The National Trust writes of it: "Most of what you see of the grand building today dates back to the 1850s, when it was given a fashionable Gothic facelift, with stone cladding and four impressive turrets".

The nearby dairy cottage, ha-ha, dovecote, fountain, deer abattoir, icehouse, home farmhouse, corn barn and byre/stable range are Grade II listed in their own right.

[4] Newton House is a three-storey castellated structure,[11] built from grey stone, with a tall tower in each corner, with sloping slate roofs.

The old dining room to the right of this features a coffered ceiling dated to the 17th century, containing "low plaster relief mouldings including guilloché, acanthus and egg and dart".

The drawing room to rear of the property also features a richly adorned coffered ceiling with "frieze bearing rosette bands" and a "centre oval with bay leaf design".

[4] On the upper floors are rooms with 18th-century fittings, including "panelled dados, lugged architraves, low relief plaster ceilings and closets within angled turrets".

Aside from the tearoom, the exhibition in the basement and ground floor contains numerous displays related to the Rhys family, the history of the estate and World War II, and is designed as if the year is 1912.

[18] Writing in 1862, Benjamin Clarje considered the park to exhibit "perhaps a richer display of varied landscape than any spot of similar size in the kingdom".

He notes that the surface in the upper area of the park is "diversified by gentle undulations and has been planted with great judgment and taste" and that the River Towy flows in the vicinity.