This huge pile of volcanic boulders hides a stunning network of secret grottoes.

This peculiar lake of pitch is so thick and viscous that one can walk on its surface.

An explosion of natural color known as "the river that ran away from paradise."

Spend the night in this former asylum for the incurably insane, which claims to be one of the most haunted places in the United States.

Renowned restaurant tucked in a cave once occupied by buccaneers.

A medieval setting reimagined into a unique art alley.

Crossing a suspension bridge above a forest is the only way to reach this 12th-century monastery.

These natural cliffs look like they are a part of an old castle complex.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.

The home, museum, and death site of Kodak's influential founder.

This enchanting Victorian estate was home to the world's first hydroelectric power generator.

This restaurant was removed from the famed sister ship of the Titanic and placed within a hotel.

This enormous secondhand bookstore inside a Victorian train station sparked the "Keep Calm and Carry On" craze.

This giant wooden treehouse within a sprawling garden has its own eatery.

This iconic 1,000-year-old medieval castle is a favorite of the film industry, most notably as the location for Hogwarts in Harry Potter.

The sign at the garden gate reads: "These Plants Can Kill."

The longest hedge maze in the world.

A dark, narrow tunnel that leads to a charming lake and waterfall.

This whimsical stacked cabin looks like something out of a children's book.

This simple rock stands as a memorial of the major student protests of 1968.

Also known as the Limete Tower, la Tour de l'Échangeur can be seen from almost everywhere in Kinshasa.

George Martin's Caribbean recording studio now rots within the shadow of an active volcano.

A short tunnel built straight through a magmatic dike.

A renovated hotel is bringing new life to a nearly-abandoned mining town in Colorado.