The museum is run by South West Heritage Trust, an independent charity, and includes objects initially collected by the Somerset Archaeological and Natural History Society who own the castle.

Exhibits include the Frome Hoard, the Low Ham Roman Mosaic, the bronze-age South Cadbury shield and a range of other objects relating to the history of the county.

[2] In 1874 the castle was bought by the Somerset Archaeological and Natural History Society[3] and between 1899 and 1900 the Great Hall was repaired and refitted as their chief museum space.

[8] In October 2007, plans for a £6.5 million improvement to the museum and the castle were submitted by Somerset County Council to the Heritage Lottery Fund.

[10][12] The museum hosts a collection of toys and dolls, sculpture, natural history, fossils, fine silver, remains of pottery, and it also contains a collection of archaeological items, including the mosaic found at the Low Ham Roman Villa.