<P> During the First World War, eleven men were tried in private and shot by firing squad at the Tower for espionage . During the Second World War, the Tower was once again used to hold prisoners of war . One such person was Rudolf Hess, Adolf Hitler's deputy, albeit just for four days in 1941 . He was the last state prisoner to be held at the castle . The last person to be executed at the Tower was German spy Josef Jakobs who was shot on 15 August 1941 . The executions for espionage during the wars took place in a prefabricated miniature rifle range which stood in the outer ward and was demolished in 1969 . The Second World War also saw the last use of the Tower as a fortification . In the event of a German invasion, the Tower, together with the Royal Mint and nearby warehouses, was to have formed one of three "keeps" or complexes of defended buildings which formed the last - ditch defences of the capital . </P> <P> 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 . </P> <P> 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 . </P> <P> Public interest was partly fuelled by contemporary writers, of whom the work of William Harrison Ainsworth was particularly influential . In The Tower of London: A Historical Romance he created a vivid image of underground torture chambers and devices for extracting confessions that stuck in the public imagination . Harrison also played another role in the Tower's history, as he suggested that Beauchamp Tower should be opened to the public so they could see the inscriptions of 16th - and 17th - century prisoners . Working on the suggestion, Anthony Salvin refurbished the tower and led a further programme for a comprehensive restoration at the behest of Prince Albert . Salvin was succeeded in the work by John Taylor . When a feature did not meet his expectations of medieval architecture Taylor would ruthlessly remove it; as a result, several important buildings within the castle were pulled down and in some cases post-medieval internal decoration removed . </P>

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