Beneath the impressive baroque cathedral that rises from the center of Berlin lies the largest collection of Prussian royals in the world.

Tiny memorials honor individual victims of the Holocaust.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

The bunker where Hitler took his own life is hidden under this deliberately ordinary parking lot.

A monument to the man who almost killed Hitler.

The site of the famous Nazi book burning campaign of 1933 remembers its "Night of Shame".

One of downtown Berlin's last reminders of its Communist past.

The largest free-standing aquarium in the world resides in a hotel lobby in Berlin.

A discarded movie prop that was the original monolith for "2001: A Space Odyssey."

There's an exclusive Beefeaters pub hidden in the Tower of London.

Tucked away in the Tower of London is the weapon once used to execute high-profile prisoners.

Richard III supposedly disposed of his nephews' bodies here in an effort to seal his claim to the throne.

Graffiti from the 16th and 17th centuries cover the walls of this part of the Tower of London.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

The ritual has been performed uninterrupted for nearly 700 years.

The watery entrance for condemned prisoners heading to the Tower of London is still visible along the Thames.

These wire animal sculptures commemorate the exotic inhabitants that once called the Tower of London home.

An architectural oddity hides in plain sight on this iconic London bridge.

Public access to clean drinking water was an instant hit among the masses.

This landmark church concealed a crypt packed with bones that was discovered thanks to the London Blitz.

The taxidermied remains of a once-great parrot.

One of the few remaining examples of 19th-century London’s attempt to clean up its reputation.

A 300-year-old tea shop that brought tea to the English people, not to mention the Queen herself.

This striking statue brings a scene from the African savannah into central London.