Witham in Somerset was the site of the first Carthusian monastery in England. Following the Dissolution, the priory was replaced by a succession of great houses, incorporating parts of the monastic buildings. A recent survey and analysis have established for the first time the site and orientation of these houses, and confirmed the location of another house nearby, designed by Robert Adam. The work has also shown that, contrary to earlier thinking, an early eighteenth-century remodelling of the house by James Gibbs was in fact carried out, and that the Adam one, too, was substantially completed. The survey also revealed details of the gardens and lakes that accompanied one house, and aspects of an unfinished park which was planned as the setting for the Adam mansion.