The redoubt is a circular structure, measuring 224 feet (68 metres) in diameter and is built almost entirely of brick with some granite facing.

The lower tier is composed of a ring of 24 casemates or vaulted chambers, which open into a central parade ground.

[6] The floor of the ditch is traversed by five caponiers or covered galleries with loopholes that allowed the defenders to fire at any attackers who had reached that point.

Access to the main gate of the redoubt is across a wooden drop bridge,[4] which is a modern reconstruction of the original, built in 2003 with help from the Royal Engineers.

[6] The decision to build the redoubt was made at a conference held in Rochester on 21 October 1804, to discuss defence against Napoleon's planned invasion of the United Kingdom, preparations for which were gaining momentum on the opposite side of the English Channel.

The meeting, which was attended by the Prime Minister, William Pitt the Younger, agreed to adopt a revolutionary scheme to build a chain of mutually-supporting circular artillery towers along a stretch of the Channel coast where the French were thought to be most likely to land.

[7] The 11-gun towers, which came to be known as "circular forts" or "grand redoubts", were intended to act as barracks and stores depots for the rest of the Martello chain, as well as formidable fortresses in their own right.

[12] These were replaced shortly afterwards by longer ranged 36-pounder guns, after fears the redoubt could be bombarded at a distance by heavier French weapons.

[1] The main role of the redoubt was as a barracks rather than a fortress, with troops being stationed there for a few weeks at a time while using nearby training facilities.

In 1859, the Royal Commission on the Defence of the United Kingdom which had been set up by Lord Palmerston to review Britain's fortifications, reported that the redoubts and Martello towers were "not an important element of security against attack".

In 1957, the redoubt was leased to an entrepreneur named Benjamin White, who created a model village on the parade ground and constructed a new entrance from the moat, with a staircase that gives access from the promenade.