Fort Cumberland, a Scheduled Ancient Monument, is a well-preserved listed Napoleonic bastioned fort protecting vulnerable coastland to the east of Portsmouth, incorporating numerous Grade II* listed structures from a mid-eighteenth century predecessor, with nineteenth century and later alterations and additional buildings.
The fort is pentagonal in plan, its bastioned defences enclosing 24 acres. Surrounding the fort is a dry ditch with covered way, a glacis protecting the approach to the fort and, on the west side, a ravelin designed to protect the approach of the entrance road to the original main gate. Five bastions (central, north, south, left and right) at the points of the pentagon are linked by sections of curtain wall, all formed from shingle mixed with lime, with stone revetment to external faces, brick to rear and crowned with a grassed terre-plein.
In 2012, Alastair Coey Architects were appointed to the condition survey framework of Conservation consultants for the South East Region of England by English Heritage. Alastair Coey Architects have held an ongoing role within the framework, providing elemental and condition surveys as part of the K2 asset management database system currently operated by English Heritage.