A castle from the Holy Roman Empire that hosts traveling youth... in its stables.

This lurid German fountain plots the sad course of marriage from dating to death.

Scattered throughout London are ancient remnants of the city's former bounding wall.

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

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

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

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

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

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

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

A building claimed to be London’s smallest house has an obscure history.

London's last remaining public soapbox site has seen speeches from Karl Marx, Vladmir Lenin, and George Orwell.

Once designed as the entrance to Buckingham Palace, this structure was later relocated and stands as a victory arch.

A statue of the legendary Celtic warrior queen who fought the Roman invaders stands in one of the cities she once destroyed.

At almost 1,000 years old, this is the oldest known door in all of Britain.

The "beautiful" equation predicting the movement of all electromagnetic particles is engraved in front of Newton's tomb.

Giant, friendly pelicans in Central London, the most unlikely of places.

The niches over the western entrance of Westminster Abbey honor individuals from the 20th century who gave their lives for their Christian beliefs.

This centuries-old gothic monster has been converted into a sprawling, glossy bookstore.

Corn-inthian columns with a uniquely American take on neoclassical architecture.

This statue of the "father of television" stands prominently in the United States Capitol.

Rumor has it the uncarved lump behind the three famous suffragists is reserved for the first woman president.

A little marble compass above George Washington's (empty) tomb in the Capitol marks where D.C.'s four quadrants intersect.

The actual model from the original "Star Trek" series is now on display at the National Air and Space Museum.