iron battleship to be built in a Royal Dockyard. It now houses . No 3 Dry Dock 1820, the first to be constructed of stone, was designed by John Rennie. It now houses HMS Ocelot. No 4 Dry Dock 1840 was built on the site of one of a parallel pair of docks built in 1686 (the second of which was converted into the adjacent slipway, No. 3 Slip). It now houses . South Dock Pumping Station 1822, designed by John Rennie. It originally housed a beam engine, which was replaced by an electric pump in 1920. The building is still in use. Offices and residential Commissioner's House 1704. This is the oldest surviving naval building in England. It is Grade I listed. It was built for the Resident Commissioner, his family and servants. The previous building was built in 1640 for Phineas Pett. In 1703, Captain George St Lo took up the post and petitioned the Admiralty for a more suitable residence. Internally the principal feature is the main staircase with its painted wooden ceiling attributed to Thomas Highmore (Serjeant Painter), to sketches by Sir James Thornhill. Commissioner's Garden dating from 1640. The lower terraces are one of the first Italianate Water Gardens in England. There is a 400-year-old mulberry tree, from where Oliver Cromwell reputedly watched the Roundhead Army take Rochester from the Royalists. There is an 18th-century icehouse and an Edwardian conservatory with its great vine. Officers' Terrace 1722–23. Twelve houses built for senior officers in the Dockyard. The ground floor were built as offices, the first floor contained reception rooms with bedrooms above. Each has an 18th-century walled garden, which again are now very rare. They are now privately owned. House Carpenters' Shop . Built to harmonise with the officers' terrace. House Carpenters worked solely on maintaining the dockyard buildings. Stables. For officers' horses. Main gatehouse 1722, designed by the master shipwright in the style of John Vanbrugh. It bears the arms of George III. Inside the gateway stands the muster bell on a wrought iron mast dating from the late 18th or early 19th century; it is Grade II* listed. Guard House 1764. Built when Marines were introduced into the Dockyard to improve security. It continued in use till 1984. Cashiers' Office 18th century. The Pay Office was moved here in 1750 from Hill House, and remained here until the yard closed. John Dickens, father