A scattered trail of street art adds a pop of color to the city's stark structures.

The elaborate clockwork contraptions in this Scottish gallery create small worlds of whimsy and horror.

An 80-year-old plane tree is devouring an iron bench at Ireland's oldest law school.

The largest clown school in Britain offering accredited degrees.

This museum tucked below a charming cafe gives a brief snapshot of photographic history.

A movable feast that is an East London institution.

An eccentric 18th century naval officer built a ship's quarterdeck on his roof, the inspiration for Mary Poppins's "Admiral Boom."

This elaborate Byzantine-style building was designed for a not-so-pretty purpose.

This hidden green space is the city's second largest conservatory.

The bar where "The Great Train Robbery" was planned was once a nexus of high society and low morals.

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

A closed London rail station created to cart away the dead still bears the marks of attempts to make it less morbid.

The remains of Crystal Palace Great Exhibition of 1851.

A cluttered and astounding collection of antiquities and curiosities.

A mysterious artist-run cabinet of curiosities and library.

Remnants of a Victorian garden feature sitting in public woodland.

A historic house left in "dramatic still life."

In this cobwebbed old operating theater, you can practically hear the screams of the unanesthetized patients.

One part local history, 99 parts gruesome haunted house.

A hands-off space for graffiti artists to hone and display their skills.

A kaleidoscopic warehouse-maze of handmade neon signs.

This churchyard arbor is surrounded by hundreds of gravestones placed there by author Thomas Hardy.

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

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