England's most famous front door has an accidental doppelganger.

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

The plunge pool is a surviving relic of a rowdy royal residence.

The commemorative stone column conceals a secret laboratory.

The pretty iron lamp is a reminder of the architecture underneath London's streets.

A relic of Victorian grandeur hides beneath a busy South London road.

The secret wartime bunker built on the platforms of an abandoned Tube station.

The wooden telephone box hidden away in London's Piccadilly was the original prototype of the iconic kiosk.

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

The fierce beast perches atop a pedestal marking where the historic City of London gates once stood.

Eighty million natural history specimens call this gargantuan museum home.

A charming 17th-century alley is lined with secondhand bookstores and antiquarian shops.

This London pub hides a peculiar secret: a recreation of the rooms shared at 221b Baker Street by Sherlock Holmes and Dr. Watson.

This memorial museum chronicles the apocalyptic destruction of the First World War.

Tucked in the back of a flower shop, its collection details the fascinating history of the Netherlands's iconic symbol.

Enter the cabin of a life-sized Hindenburg replica.

Go surfing on this urban wave, "hacked" by local surfers.

The fairy tale castle of the "fairy-tale king."

It's good luck to be mocked by this monkey.

This tribute to the 16th-century composer is now an unusual shrine to Michael Jackson.

The 1852 novel "Uncle Tom's Cabin" lends its name to a subway station, a street, and several shops on the edge of Berlin.

This curious sculpture represents the perseverance needed to take to the skies.

One of the world's heaviest musical instruments towers within a popular urban park.

Metro station with a claim to rock n' roll fame.