In 1066, a new king strolled into London. He was William the Conqueror, an invader from Normandy. He had defeated England’s King Harold II at the Battle of Hastings. Now he had to secure his status as ruler of England.

To do that, he built a fortress.

Construction started that same year. The Tower of London soon loomed over the city’s skyline. Though called a tower, it’s really a castle. Its many walls and wide moat made it easy to defend. It gave Londoners a symbol of their new king’s might.

Throughout the Tower’s nearly millennium-long history, it served many purposes. For centuries, the Tower Mint produced most of England’s money. The Tower also held a zoo. Royals often received exotic animals as gifts. Those animals needed a place to stay. The Tower had lions, an elephant, and even a polar bear!

Kings and queens also lived within its walls—and not always by choice. The Tower became a legendary prison. One of its famous prisoners was Anne Boleyn. She was Queen of England alongside King Henry VIII. The king accused her of treason. Most historians say the claims were false. But an executioner beheaded her on the Tower grounds.

The tower guards are known as “Yeoman Warders.” Some folks call them “beefeaters.” Nobody knows why for sure. Some say the guards ate a lot of meat in the Tower’s early days.

Today, about three million tourists visit the Tower of London every year. It’s no longer the tallest building in London. But what it lacks in height, it makes up for in history.

For more about this famous landmark, see A Raven History of the Tower of London by Mark Osborne in our Recommended Reading.