This former train tunnel is filled with lines from a poem crafted by Robert Louis Stevenson.

This 19th-century sanctuary was built atop a hill that once housed a Roman fort.

This former school is now abandoned and a canvas for graffiti artists.

Medicinal spa created with the discharge from a geothermal energy plant.

Looking strangely like Rome's Colosseum, this unfinished tower has dominated the skyline for over 100 years.

This alley off Edinburgh's Royal Mile contains remnants of the city's seedier history.

This 16th-century house tells the city's history through old artifacts and quirky tales.

This Scottish graveyard is the final resting place of the man who inspired the character Ebenezer Scrooge.

This dramatic landscape hidden on the Isle of Skye looks as though you've stepped into the magical realm.

Ancient cliffs resembling a kilt on Scotland's second largest island emit an entrancing sound.

An ancient Scottish rock formation said to be the gravesite of a giant remains ensconced in legend and intrigue.

Islanders once used this dramatic, otherworldly landscape to hide their cattle from Viking raiders.

The ruins of the second of three churches dedicated to the saint in a touristic Scottish town.

Journey through one of the oldest industrial sites in Scotland.

The "Bridge Over the Atlantic" lets you cross the waterway in mere seconds.

The 2,000-year-old Roman columns are hidden within Barcelona's Gothic Quarter.

Mountain where Jesus was first tempted by the Devil.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

Go inside to really appreciate this 500-year-old technological masterpiece.

Venice's "Island of the Mad."

The complex has been abandoned since the Croatian War of Independence, barring a stint as a set for 'Game of Thrones.'

This Venice bookstore has resigned itself to constant flooding by keeping its books in bathtubs and boats.