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

The commemorative stone column conceals a secret laboratory.

The 2,000-year-old beam is tucked within the pedestrian entrance to the old London Bridge.

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.

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

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

The library houses an incredible collection of some of the world's most impressive books and manuscripts.

This legendary stone is of unknown origin, and throughout history has been a literal touchstone for British leaders.

An alleyway plaque is all that remains of the independent Texas' envoy that forgot to pay their rent for over a century.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

Kings Cross Station pays tribute to its role in Britain's best-selling book series.

One of the few remaining casualties of the London Blitz, this destroyed church has become an enchanting public garden.

The colorful stairs are made with marble from the world's major quarries.

Brass bricks outline the locations of Edinburgh's lost, lively market stalls.

A six-ton wedding present for the King of the Scots.

Overlooked by many, the two famous Scottish warriors guard the main gate of Edinburgh Castle.

A sweet symbol marks the place where torturous executions were once carried out.

This obscure walkway links Edinburgh’s Old Town with one of the city's prime vantage points.

A 18th century graveyard and its astonishing cortege of macabre iconography.

Touching this 18th-century Scottish philosopher’s toe allegedly conjures good fortune.