Archaeological investigations between 1968 and 1973 uncovered its foundations, unaltered since the medieval period, and the site is now managed by English Heritage and open to visitors.

[3] Shortly after the Norman conquest of England, however, a ringwork castle was probably built at Penhallam by the invaders, and a substantial manor was recorded as being present there in the Domesday survey of 1086.

[9] Tyrold and Richard fitz Turold founded what eventually became known as the Cardinham family, who became powerful Cornish landowners and agents for the Crown.

[9] Robert's son, Andrew de Cardinham, inherited the family's estates around 1226 and carried on expanding Penhallam, building a new hall, a service wing - including a kitchen, buttery, pantry, and a combined brewhouse and bakehouse - a chapel, lodgings, and a gatehouse.

[2] By around 1234, the result was a substantial, sophisticated manor house, with a large quadrangle of ranges, approximately 158 by 125 feet (48 by 38 m) across, facing onto an internal courtyard.

[2] By the 14th century, Penhallam was occupied by the Beaupré family, tenants of the Champernownes, and by 1330 the manor had begun to be subdivided into smaller units of land.

[23] In the mid-20th century, plans were drawn up to clear the area around the former house, then owned by Roger Money-Kyrle and managed by Economic Forestry (South West) Ltd., in order to plant a new forest.