The keys to the historic Tower of London were stolen last week, British authorities announced today. This matters to Britons. The castle has played a critical role in the nation's history and houses the queen's Crown Jewels.

Police are now investigating how, exactly, a burglar broke into the well-guarded castle last Tuesday and managed to steal several keys from the site's sentry box before being apprehended.

The burglar was reportedly spotted by the Tower's famous guards, known as Beefeaters, but the guards did not immediately stop the suspect, instead staying at their designated posts and radioing for help.

Without a chase, the burglar made off with keys to the Tower's drawbridges and conference rooms and a restaurant, according to Historic Royal Palaces, the non-profit organization that operates it. The Tower is one of the world's major tourist attractions, with more than two million visitors each year.

The burglar, who struck in the early morning hours, managed to make it all the way to the gate at the main entrance before being apprehended, a Historic Royal Palaces spokeswoman told the AFP.

"The intruder did not gain access into the Tower itself," the spokeswoman said. "He did manage to get round the gate at the main entrance but was then apprehended and escorted off the premises."

Officials say that the burglar at no time had access to the Crown Jewels, the crowns and scepters used by Queen Elizabeth II on ceremonial occasions, according to the AFP.

"It would not have been possible to gain access to the Tower with any of these keys. All the affected locks were immediately changed," the charity said in a statement.

The Tower of London is guarded by both the Yeoman Warders, nicknamed Beefeaters, who each must have completed a minimum 22 years' military service to guard the Tower, and a private security firm.

Historic Royal Palaces defended its security protocol but also acknowledged the procedures were, in this instance, "not carried out to the expected standard," and said they are pursuing a "staff disciplinary procedure."

A police investigation is also underway.

The Associated Press contributed to this report.