A labyrinth hides in plain sight at each of the city's 270 Tube stations.

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

An easily overlooked stretch of ornate window fronts and gaslight lamps that could be right from the pages of Dickens.

London's smallest police station is barely the size of a phone booth.

These official units of measurement—including chains and perches—lie hidden beneath tourists' feet in a popular London hub.

A tongue-in-cheek arcade where the games are based on everyday life.

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

This small museum in a former church crypt contains artifacts of the Elephant Man, Jack the Ripper and Florence Nightingale.

A friendly pub with a sordid past in cock fighting.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the Harry Potter films.

The home of one of America's most wealthy industrialists is now a historic site that remembers a more decadent time in the country's history.

Forgotten under the construction of a new urban roadway is a small, abandoned part of town.

The small alleys in Lübeck's Old Town are a result of medieval urban sprawl.

The world's biggest pet store.

A strange rock formation with numerous legends trying to explain it.

Constantly maintained, this organ is playing a six-century long composition by John Cage.

Money made from smuggling sugar helped create this wondrous rock maze in honor of the Prussian Queen Louise.

This temple to the sturm and drang of Richard Wagner contains a dragon's cave and reptile zoo full of living "dragons."

A Black Forest cuckoo clock theme park features one timepiece big enough to walk inside.

No need to strap in for a "ride" on this walkable roller coaster.

An intricate and amazing house built by architect Karl Junker.

This medieval castle overlooking the Elzbach river looks just like it did hundreds of years ago.

A sprawling Baroque park with 300-year-old hydro-pneumatic waterworks.

This once-grand marvel of engineering is now 41 miles of scenic hiking trail.