Within the last couple of years, the original 15.4 hectares (38 acres) of Williamson Park have been supplemented by 6.3 hectares (15.6 acres) of less formal woodland.
Fenham Carr, part of the Lancaster Moor Hospital grounds until it closed in 2000, has presumably been virtually undisturbed since the Corporation of Lancaster donated it to the County Palatine for the new Asylum in the reign of George III.