The Taelemans´ Blog

The White tower, built by William the Conqueror in 1078, is the the original stark square fortress of the Tower of London.

The Tower of London’s primary function was a fortress, a royal palace, and a prison (particularly for high status and royal prisoners, such as the Princes in the Tower and the future Queen Elizabeth I). This last use has led to the phrase “sent to the Tower” (meaning “imprisoned”). It has also served as a place of execution and torture, an armoury, a treasury, a zoo, a mint, a public records office, an observatory, and since 1303, the home of the Crown Jewels of the United Kingdom.
(Source: Wikipedia)