An agreement meant to honor the Duke of Buckingham led to this unusually-named passageway near Charing Cross.

These ornate arches show how the course of the River Thames has changed.

A mysterious pair of mice eating a piece of cheese is London's smallest public sculpture.

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

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.

Only a few pieces remain of the structure that carried people and goods across the Thames for some 600 years.

Hear the quietest sound from across the dome.

A building that survived WWII, possibly on the virtue of its name alone.

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

Order a salt beef-loaded beigel at any hour of the day or night at this East End institution.

It celebrates a very stinky task and salutes London's fatberg-vanquishing team.

Legend says these colorful, invasive residents are the descendants of birds released by Jimi Hendrix.

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

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

A mysterious artist-run cabinet of curiosities and library.

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

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

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

Claiming to be the oldest hat store in the world, this historic haberdashery had a hand (and a head) in the creation of the Bowler.

More than a million titles fill the labyrinthine shelves of this prestigious private library.

This statue includes the molehill that toppled a king.

After nearly 60 years, there's still a bear at Paddington Station looking for help.

A place to eat for on-the-run agents and espionage enthusiasts.