has anyone ever seen any ghost there?
Yes, they include ghosts of Anne Boleyn, Henry VI, Lady Jane Grey and others.
Tower of London
Anne Boleyn was beheaded in 1536 for treason against Henry VIII; her ghost supposedly haunts the Church of St Peter ad Vincula in the Tower, where she is buried, and has been said to walk around the White Tower carrying her head under her arm. This haunting is commemorated in the 1934 comic song "With Her Head Tucked Underneath Her Arm". Other reported ghosts include Henry VI, Lady Jane Grey, Margaret Pole, and the Princes in the Tower. 
when was the foundation laid for tower of london? Towards the end of 1066. what was it used for? As a royal residence as well as a prison. did it house any jewels? Yes, it houses the Crown Jewels of the English Royal family.
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Tower of London [SEP] Ghosts
Anne Boleyn was beheaded in 1536 for treason against Henry VIII; her ghost supposedly haunts the Church of St Peter ad Vincula in the Tower, where she is buried, and has been said to walk around the White Tower carrying her head under her arm. This haunting is commemorated in the 1934 comic song "With Her Head Tucked Underneath Her Arm". Other reported ghosts include Henry VI, Lady Jane Grey, Margaret Pole, and the Princes in the Tower. In January 1816, a sentry on guard outside the Jewel House claimed to have witnessed an apparition of a bear advancing towards him, and reportedly died of fright a few days later.