This natural sea arch highlights Ireland's rugged coastal beauty.

The world's tallest box hedge is found in a delightful garden.

This 30-foot pile of rocks may be the grave of a mythological Irish queen.

There might not be much left of these Irish ruins, but their linguistic legacy is still going strong.

This controversial Irish show cave is home to a massive formation known as the Great Stalactite.

The world's toughest modern Christian pilgrimage leads directly to the gates of Hell.

The 19th-century pharmacy (now a used bookstore) was featured in James Joyce’s "Ulysses," and has changed very little to this day.

While only two of the ancient buildings at this site are actually churches this was one of the earliest Irish pilgrimage sites ever.

The oldest public library in Ireland.

The oldest pub in Ireland may also be the oldest surviving bar in the entire world.

The ancient tomb acts as a calendar that keeps perfect time.

A tiny microvalley etched into the side of Knocknarea Mountain hides another world.

An eccentric garden of sculptures crafted in India decorate an Irish green space dedicated to Alan Turing.

The enchanting archway is the only surviving portal into Dublin's lost medieval wall.

A tiny theater hidden in an alley plays a constant stream of short silent films for anyone willing to peer through the peephole.

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

A museum dedicated to the strange and extravagant costumes and memorabilia of the mummers, a tradition older than Philadelphia itself.

This sculpture of a fisherman spent six years at the bottom of the Schuylkill River.

One of Philadelphia's largest murals resides hidden under this bridge.

A cavernous three-story, 43,800-square-foot basement that was forgotten about for 60 years.

Decades before the scandal, this staircase on the river was a literal "water gate."

Remains of military submarines built in secret jungle factories by the Tamil guerrillas' naval wing.

The first and only planetarium in Sri Lanka.

Spend the night inside a two-story elephant villa.