With its associated works, Fort Clarence froms a promontory fortress streching from the Medway to the Maidstone road. It consisted of a flat-bottomed ditch 40ft wide and 30ft deep. In the center of the line and rising from the floor of te ditch is the great brick keep, 60ft high, known as Fort Clarence. Pentagonal in plan, 3 storeys high, it was desinged to house 3 tiers of guns firing E and W to enfilade the ditch. Cross fire to theangles of the ditch was provided by two smaller forts, oth buit inside the ditch. Each of these forts except that on the Maidstone road has an elaborate network of underground galleries and magazines and two of them had complicated sally-ports leading out to the southern lip of the ditch. Fort Clarence was completed in 1810, the ditch had been dug and the terminal forts built by 1812 and the intermediate forts had been built and the line virtually complete by 1815. Successive demolitions and filling in of greater part of the ditch has left only the brick keep of Fort Clarence.