The monument includes a beacon and pillbox situated on the summit of a hill on the northern bank of the River Medway, overlooking the river estuary and its hinterland. The beacon is a large, circular mound c.30m in diameter and surviving to a height of c.6.5m. The mound originally supported a fire basket, or brazier, set on a pole, although this superstructure no longer survives. The site of the beacon is shown on two maps of Kent dating to c.1570. Situated on the flattened summit of the mound is a World War II pillbox which was used mainly as a look out post for the observation of approaching enemy aircraft. The pillbox is a low, octagonal building measuring c.4m in diameter, constructed of reinforced concrete. The interior is entered by way of an iron door on the southern side of the building, and an iron ladder gives access to the flat roof, which is edged with iron railings. A large, square, central well through the roof provided for the mounting of a light anti-aircraft gun, which no longer survives. Each of the eight walls is pierced by rectangular machine gun slits, protected on the inside by top hung, iron shutters. The floor is of concrete sleepers interspersed with wooden beams. The modern fence which crosses the monument is excluded from the scheduling, although the ground beneath it is included. ASSESSMENT OF IMPORTANCE Beacons were fires deliberately lit to give a warning, by means of smoke by day and flame by night, of the approach of hostile forces. They were always sited in prominent positions, usually as part of a group, chain or line which together made up a comprehensive early warning system covering most of the country. Beacons were extensively used during the medieval period. Their use was formalised by 1325 and although some were used later, for example at the time of Monmouth's Rebellion in 1685 or during the Napoleonic wars, the system was in decay by the mid 17th century. Beacons were initially bonfires of wood or furze, but later barrels of pitch or iron fire baskets mounted on poles were used. The poles were occasionally set on earthen mounds. Access to the fire basket was by way of rungs set in the pole, or by a stone ladder set against the beacon. More unusual beacon types include stone enclosures and towers, mainly found in the north and south west of England. Some beacon sites utilised existing buildings such as church towers. Beacons were built throughout England, with the greatest density along the south coast and the border with Scotland. Although approximately 500 are recorded nationally, few survive in the form of visible remains. Many sites are only known from place-name evidence. Given the rarity of recorded examples, all positively identified beacons with significant surviving archaeological remains are considered to be of national importance. Despite some disturbance, the beacon at Frindsbury Extra survives comparatively well and will contain archaeological remains and environmental evidence relating to the monument and the landscape in which it was constructed. The siting of a later pillbox directly on the earlier beacon site illustrates the continuing importance of Beacon Hill as an early warning and defensive site into the 20th century.