Although it’s well known as one of the world’s oldest and most famous prisons, the original purpose of the Tower of London was not to house criminals. In fact, the Tower was actually built in the latter part of the 11th century as a fortress to protect London, the capital city of the British Empire – but soon became notorious for its other, more brutal, uses.

Located on the north bank of the River Thames, the Tower is actually a complex of several towers and structures. Construction on the “White Tower” began in 1078 under the rule of William I the Conqueror and it was originally intended for military use as a battlement. However, when King Henry I assumed the throne in 1100 following the assassination of his brother, William II, one of his first acts was to order the arrest of Rannulf Flambard, the Bishop of Durham. Flambard was charged with the crime of simony, or the act of selling administrative positions in the church for money and – you guessed it – he became the first prisoner held in the Tower of London. (He did escape though.)

As time went on, future monarchs continued to fortify and expand the complex. Over the following centuries, the castle grew so much that the complex that we call the Tower of London is actually made up of 21 different towers in total. Throughout its history the tower was used to imprison a wide range of prisoners, from deposed monarchs to more common criminals. During the Tudor age, the Tower became the most important state prison in the country and anyone thought to be a threat to national security came here. And although The Tower became notorious as a site of torture, historical records suggest relatively few inmates were actually tortured here.

Unfortunately, while torture may have been rare here, executions were not. Scores of prisoners were executed at the site, by beheading, firing squad, or hanging – including notable characters such as Sir Thomas More, Anne Boleyn, and Guy Fawkes. Since 1485, security at the Tower of London has been handled by special order of guards known as the Yeomen Warders – more commonly known as “the Beefeaters.” They were originally part of the Yeomen of the Guard, the monarch’s personal bodyguard who traveled with him. The name of the Beefeaters is allegedly based on a comment from an Italian nobleman in the 17th century, who remarked that members of this elite security corps were given a large daily ration of beef.

Today, the Tower now attracts over three million visitors a year who come to see the Crown Jewels, the Tower’s pampered ravens, the Ceremony of the Keys and it’s many other notable traditions.

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