This massive subterranean fissure is known as the "underground Grand Canyon."

Castle and secret tunnel withstood a siege until its owner was killed by the Holy Roman Empire, while sitting on the toilet.

One of the best-preserved Roman amphitheaters is still used today, but for less brutal events.

When a supermarket opened up shop within a medieval building it became protected by UNESCO on a technicality.

Formerly Yugoslavia's "forbidden island," this sleepy little city still holds the abandoned remains of military strongholds.

Longest fortress system anywhere in Europe.

A musical instrument played by the sea.

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

A once-thriving hotel in the Swiss Alps couldn't compete with climate change.

The alpine falls where Sherlock Holmes apparently met his demise can actually be visited.

This memorial commemorating fallen Swiss Guards of the French Revolution has been called the saddest stone in the world.

Two geological phenomena in one precarious locale: a towering stone window, and a deep blue void.

The ruins of a megalithic monument sit right in the garden of a luxurious Maltese resort.

The fishing boats that moor in this small lagoon enter and leave through a tunnel to the sea.

Stone Age solar temple is aligned with the sun on each equinox and solstice.

An abandoned set from the 1980 film "Popeye," claimed and repurposed as a theme park by creative locals.

According to legend, this boat-shaped henge is built over the grave of a mythic king.

It is said that each of the white stones in the red facade of this medieval house represents the head of a murdered Swedish noble.

Danish tourist destination well known for open stalls where vendors sell marijuana on the street.

This dazzling Buddhist temple was constructed from over one million ceramic tiles salvaged from a British shipwreck.

Thailand's distressed elephants find peace at this Chiang Mai sanctuary.

Six times a day a train runs right through the middle of this Thai street market, sending vendors scrambling.

Historic fortifications form the boundary of Vatican City, but it’s not entirely surrounded by walls.

Breathtaking and huge 430 year old maps of Italy.