Fort Halstead: Buildings F16 and F17

Fort Halstead: Buildings F16 and F17 are located on a prominent hilltop within the North Downs, north-west of Dunton Green, as part of the late 19th-century Mobilisation Centre (Fort Halstead) and its associated research facility.

Building F16 is a bomb chamber, a reinforced rectangular concrete structure designed for detonation testing, featuring a single, E-shaped armoured chamber. Access is provided by an external metal staircase attached to the south-east elevation, leading to a flat roof with metal railings along the rear (north-east) and sides (south-east and north-west). The rear and side elevations are characterised by three horizontal rows of square metal plates with central bolts, believed to be fixings for detonation monitoring equipment. Electrical inlets and outlets are also present in the rear elevation.

Building F17 is a bi-partite structure of reinforced concrete and brick. The southern and western sections consist of a single-storey, flat-roofed structure containing an armoured laboratory constructed in reinforced concrete. The east and south sections are faced in red brick in English bond, while the north elevation is in concrete; the west elevation was not inspected. A large, prominent T-shaped funnel protrudes from the flat roof. The main entrance is through folding wooden doors on the east elevation. A porch has been added to shelter a pedestrian doorway on the south side. The building rises to two storeys at its north-east corner, also in red brick English bond. All windows are metal-framed casements with concrete heads.

The interior of Building F17 was not inspected, but it's known that the bursting chamber, divided into ‘large’ and ‘small’ sections on original plans, is located in the single-storey area. Each section includes armoured glass observation windows and flanking camera rooms. Explosions were recorded using an angled mirror and a high-speed camera. The two-storey tower contained a photographic dark room on the ground floor and a control room above, from which the trials were overseen.