A 1,215-foot tunnel transports pedestrians beneath the River Thames.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the first ‘Harry Potter’ film.

The ship built to ferry passengers and goods to the doomed Titanic is now the last remaining White Star Line vessel.

Belfast's namesake river still winds below the city center, hidden from sight.

A giant sculpture of the legendary "Salmon of Knowledge" celebrates the return of fish to Belfast's River Lagan.

These engineering masterpieces are a dominant feature of the Belfast skyline.

It was once nicknamed "the most bombed hotel in Europe."

These barriers stand as stark reminders of Northern Ireland's troubled past.

A museum marks and documents the site of the Titanic's launch.

Seat of the Duke and Duchess of Devonshire for centuries.

The medieval woodcut-style artwork chronicles life in medieval London.

This print shop boasts one of the largest pinball arcades in San Francisco.

Visible below the waves are memorials to the city's Gold Rush dead.

An essential stop before plundering, BYO Cutlass.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

A huge musical instrument played by the ocean.

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

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

London's old-school healing garden.

Eighty million natural history specimens call this gargantuan museum home.

The curios of pharmacist and collector Henry Wellcome.

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

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

This South London cemetery holds the remains of more than 15,000 people.