The monument includes the Brunel Sawmills, a Grade I Listed building situated on the eastern edge of Chatham Dockyard. The sawmills were constructed in 1812-14 to a design by Sir Marc Isambard Brunel (1769-1849) and feature a series of steam-powered sawmills housed in a central single-storey building, with a two-storey block containing offices at each end. The west block, which was later extended to the north, also housed the steam engine, and has a tall brick chimney at its southern end; the roofs of both blocks take the form of iron water tanks which served the boiler. The sawmills went out of use after the decline in the demand for timber for shipbuilding in the late 19th century, and the building was partly reused as the dockyard laundry and store. Extensions to the north and south west sides of the west block are believed to date from the late 19th and early 20th centuries. In order to accommodate the sawmills, the dockyard was extended to the east with a new surrounding wall constructed; the line of the former 18th century dockyard wall falling within the scheduled area. Brunel's design for the sawmills included the construction of a canal for floating timber to the sawmills from the South Mast Pond, 150m to the north west. The South Mast Pond is scheduled separately. The canal was built between 1812 and 1814, extending from the South Mast Pond towards the sawmills situated on a hill to the south east. Adjacent to the South Mast Pond it took the form of an open channel, now infilled, and was then carried under the road; for the most part, however, it was contained in anunderground brick-lined tunnel cut into the side of the hill, terminating in a vertical brick-lined shaft of elliptical plan through which the timber was finally raised. The machinery which lifted the timber was powered by the same steam engine that powered the sawmills. From the shaft the timber was carried to a storage area (the stackyard) north of the sawmills on an overhead railway, also by steam power. The remains of most of this machinery is no longer evident, although parts may survive inside the infilled shaft. The full extent of the tunnel is included in the scheduling. The central sawmills building is a brick-built structure with cast iron columns and beams. It is of square plan, measuring approximately 29 sq m, with openings on the north and south sides which are now closed and partly glazed. The sawmills machinery was contained in this central structure, where pairs of vertical iron frames extended from basement to ground floor level, where they supported a series of reciprocating saw-frames. The machinery was connected to the steam engine at basement level. The first 24-horsepower steam engine was replaced in the 1820s by a 36-horsepower engine, and some of the machinery was replaced after a fire in 1854. While the steam engine and much of the machinery was emoved when the sawmills went out of use, the large vertical frames still survive. Other features associated with the use of the building as a sawmills include a series of wooden offices at gallery level within the central building, and, adjacent to the south west of the building, a rectangular raised yard with a vaulted basement beneath. At the eastern end of the yard is a series of small outbuildings beneath a ramp running from the shaft area to the north. These features are believed to be associated with the transport and storage of timber at the site and with the operation of the water system which powered the machinery. In the 20th century the tunnel connecting the sawmills with the South Mast Pond was adapted for use as a civil defence communications centre, first during World War II and subsequently in the early Cold War period. While the open canal at the north end of the tunnel and the shaft at the south end were infilled, the bottom of the tunnel was partly filled with loose material and covered with a concrete floor. The whole of the upper part of the tunnel, and part of the lower level, were fitted with a series of brick-walled chambers, separated by alternating interval entrances, rising to ground level via a series of staircases, now blocked. In the southern part of the tunnel, staircases led downwards to a control room at the lower level. Some internal fittings associated with the communications centre survive, including blast doors, desks, wall charts and telephonic equipment. All modern surfacing, fencing, kerbs and street furniture, and the modern wall on the south west side of the raised yard south of the saw mill are excluded from the scheduling, although the ground beneth these features is included. The 20th cenury entraces to the tunnel, associated with its use as a communications centre, are however included.