The Tower of London is a medieval fortress in the heart of London. It originated as the White Tower, a stone castle built by William I in 1078 to overawe his recently conquered capital, but was subsequently enlarged and strengthened. It served as a fortress, a palace and a prison over the centuries.
The Tower served as a royal palace from its foundation until the rule of Oliver Cromwell, and it housed the royal menagerie from the early thirteenth century until 1835. Today the Tower is home to seven ravens, for an old legend says that if the ravens leave then the Tower will fall and with it the kingdom.