Castellau dates from the seventeenth century and is a good example of a late Classical style of building. The plan is formed by a long south block and rear wings on the northern side, flanking a central stair hall. It Early in the nineteenth century the south elevation was refenestrated with French windows and a central doorway was added. A central stair unit was also added at this time, and the interior was extensively remodelled.

Susan Evans, RCAHMW, 8 June 2004