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

The commemorative stone column conceals a secret laboratory.

The Great Fire of London and the regulation of one-way streets both started in this alley.

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

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

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

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

Lovers proclaim their unbreakable bond by leaving their names on locks fastened onto the Shoreditch fence in East London.

A community of artists and entrepreneurs seeks a simpler life on London's waterways.

Tourists who rely on a transit map to find the iconic Beatles location often end up in a far-off neighborhood.

A historic London cemetery now serves as a nature park incorporating gravestones & memorial statues.

Though it's not the largest, this one-kilometer outdoor market is reportedly the longest in Europe.

A replica of the gaslit streetlamp under which three teenagers founded a football club.

This extinct volcano rises above Edinburgh and is special for its panoramic views over the city.

This sculpture commemorates Edinburgh's sister city and their respective celebrity dogs.

A statue in the heart of Edinburgh honors a bear that served in the Polish military during World War II.

The final resting place of soldiers' loyal canine companions.

Protecting the dead from opportunistic body snatchers.

The tomb of one of Scotland's bloody historic villains is a magnet for bumbling desecrators.

A verdant 17th-century-style garden hidden along Edinburgh’s Royal Mile.

This otherwise ordinary close on the Royal Mile constituted the end of the world for Edinburgh’s poorest residents.

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

Poetic, metallic giraffes adorn a square off an Edinburgh thoroughfare.

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