Natural stone arches form a walkable "cathedral" at low tide, then disappear entirely when the water returns.

Hundreds of stone stairs and a winding medieval bridge connect this haunting Spanish island to the mainland.

Mysterious Spanish catacombs of unknown origins.

An Oxford museum where visitors can have tea with the Mad Hatter and climb through the wardrobe to a fantasy land.

The subterranean "lake" below the Paris opera house inspired the Phantom of the Opera's lair.

Centuries before the modern seismograph, Armenian monks measured quakes with this tilting pillar.

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

Nestled in the heart of San Francisco’s bustling Financial District stands a unique homage to the Mayan and Beaux Arts.

You'd never know the houses at 23-24 Leinster Gardens were fakes—until you see the train tracks on the other side.

This luxury shopping lane has been protected by its own tiny police force for over a century.

The sixth of London's "Magnificent Seven" cemeteries, and a source of unlikely inspiration to Beatrix Potter.

A 2000-year-old Roman amphitheater lies just below Guildhall Yard.

This collection of illusory paraphernalia has been culled from the history of London's premier magician's club.

An unusual round church in London with a Templar past.

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

The doodles of a genius line the walls of a secret room under the Medici Chapel, where they were hidden for nearly 500 years.

Five candy-colored villages on the Italian Riviera.

The glowing blue Nymphaeum of Emperor Tiberius.

Stalactites and stalagmites in a beautifully lit cave.

A small peaceful park and waterfall tucked amid the urban grind of Midtown Manhattan.

Love, knishes, and best wishes from this legendary Lower East Side bakery.

Slyly buy a shake in the Parker Meridien lobby.

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

Elevated freight railway turned wildly successful urban park.