The Tower of London, officially Her Majesty's Royal Palace and Fortress of the Tower of London, is a historic castle located on the north bank of the River Thames in central London. It lies within the London Borough of Tower Hamlets, separated from the eastern edge of the square mile of the City of London by the open space known as Tower Hill. It was founded towards the end of 1066 as part of the Norman Conquest of England.
The White Tower, which gives the entire castle its name, was built by William the Conqueror in 1078 and was a resented symbol of oppression, inflicted upon London by the new ruling elite. The castle was used as a prison from 1100 (Ranulf Flambard) until 1952 (Kray twins), although that was not its primary purpose. A grand palace early in its history, it served as a royal residence. As a whole, the Tower is a complex of several buildings set within two concentric rings of defensive walls and a moat. There were several phases of expansion, mainly under Kings Richard the Lionheart, Henry III, and Edward I in the 12th and 13th centuries. The general layout established by the late 13th century remains despite later activity on the site.
The Tower of London has become established as one of the most popular tourist attractions in the country. It has been a tourist attraction since at least the Elizabethan period, when it was one of the sights of London that foreign visitors wrote about. Its most popular attractions were the Royal Menagerie and displays of armour. The Crown Jewels also garner much interest, and have been on public display since 1669. The Tower steadily gained popularity with tourists through the 19th century, despite the opposition of the Duke of Wellington to visitors. Numbers became so high that by 1851 a purpose-built ticket office was erected. By the end of the century, over 500,000 were visiting the castle every year.
Over the 18th and 19th centuries, the palatial buildings were slowly adapted for other uses and demolished. Only the Wakefield and St Thomas's Towers survived. The 18th century marked an increasing interest in England's medieval past. One of the effects was the emergence of Gothic Revival architecture. In the Tower's architecture, this was manifest when the New Horse Armoury was built in 1825 against the south face of the White Tower. It featured elements of Gothic Revival architecture such as battlements. Other buildings were remodelled to match the style and the Waterloo Barracks were described as "castellated Gothic of the 15th century". Between 1845 and 1885 institutions such as the Mint which had inhabited the castle for centuries moved to other sites; many of the post-medieval structures left vacant were demolished. In 1855, the War Office took over responsibility for manufacture and storage of weapons from the Ordnance Office, which was gradually phased out of the castle. At the same time, there was greater interest in the history of the Tower of London.