Rippling sand dunes frozen in the Arizona rock.

An artsy hidden staircase leads to breathtaking views of San Francisco.

A peculiar mansion built by the troubled heir to the Winchester Rifle Company fortune.

During prohibition, corrupt city officials ran drinking dens under the streets of Downtown Los Angeles.

A huge musical instrument played by the ocean.

Plot your trip through the city on the sidewalk.

Order scoops of pandan, lychee, and black sesame at this family-run institution.

Try not to get slimed in Tribeca.

La Monte Young and Marian Zazeela's "Dream House" will immerse you in an ever changing world of sound and light.

A beautiful and abandoned New York subway station from 1904, complete with chandelier.

This beautiful building in the heart of Manhattan's Financial District was empty for decades.

Tucked away in the Tower of London is the weapon once used to execute high-profile prisoners.

Tombstones and enigmatic inscriptions hide within a vault beneath a popular London arts venue.

The last four extravagant street signs of London's historic banking street.

The Florence Nightingale Museum is home to the famous nurse's most treasured possession: her beloved pet owl.

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

A community of artists and entrepreneurs seeks a simpler life on London's waterways.

The pioneer of psychoanalysis spent the final year of his life here, still seeing patients on that famous couch.

Bronze sculpture celebrating the relationship between Churchill and Roosevelt.

This landmark church concealed a crypt packed with bones that was discovered thanks to the London Blitz.

A statue marks the exact spot where The Boy Who Never Grows Up made his first literary appearance.

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.

The Metropolitan Police refurbished the blue box (perhaps not coincidentally) the same year "Doctor Who" returned to TV screens.

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