Now let's stop at Traitor's Gate. It was named this for the large number of prisoners charged with treason that were brought through here.
Back when The Tower was used as a prison, the River Thames was an important and heavily used "road" around London. Boats were a relatively effective mode of transportation. Consequently, the Gate became one of the main entrances into The Tower and was especially convenient for sending in prisoners tried at Westminister, which also lies along the Thames.
One of the more famous figures to have passed through the Gate was 21 year old Princess Elizabeth, who had been accused of aiding a rebellion against her sister, Queen "Bloody" Mary. Unlike many people who came through the gates, Elizabeth came out again alive 8 weeks later and eventually became queen.