Mostyn Hall is a large mansion of irregular heights and massing, built of stone under a slate roof. It is situated on a north-east-facing hillside above the sea, with the main entrance front facing south-east. The present house shows an extensive nineteenth-century remodelling in neo-Jacobean style of a 17th-century house with fifteenth-century fragments. The work was carried out by Ambrose Poynter for the 1st Lord Mostyn in 1846-47.

On the south-east Poynter introduced a two-storey gabled block now joined on to the rebuilt great hall. A square tower based on a drawing by Thomas Dinely in his Account of the Progress of the Duke of Beaufort through Wales (1684), was reintroduced by Poynter but this time with a truncated apex. The latest addition was the north-west wing in 1855. Although the interior is considerably re-arranged it retains some earlier features.

The earlier parts of the building include the recessed centre of the south-west front (1631-32) overlooking a small formal garden.

Associated with:
Porth Mawr/the S block (Nprn36035)
Mostyn Hall barn (Nprn37392)
Mostyn Hall stables (Nprn37393)
Other associated features are connected with the park/gardens (Nprn86624)
J.Wiles 06.11.02