A perilous medieval road leading right into the sea.

Pyramid shaped monument with a tall tale attached.

These 2000 year old remains of a Roman aqueduct are hidden inside a hotel lobby.

After 400 years of being closed to the public, this monastery's underground tunnels and secret garden are now a museum.

The medieval home is still engraved with the symbol of the profession, an eye flanked by two axes.

This almost-forgotten underground dungeon housed several convicts over the years, including Caravaggio.

This prison on the Maltese island of Gozo is almost 500 years old, and they have the graffiti to prove it.

This subterranean necropolis holds three floors of antler-dug grave caves.

The floor of this spectacular Baroque sanctuary is covered in memento mori.

As can be expected from a centuries old church built in a canal city, the undercroft of this house of worship is beautifully flooded.

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

The John Snow Memorial marks the epicenter of London's 1854 cholera epidemic.

The television series' iconic giant foot was borrowed from this classical painting.

London's old-school healing garden.

In 1889, a small group of women began meeting to discuss literature, art, and other topics. Their every-other-week salon grew into a lending library that still exists today.

This hauntingly beautiful stretch of Florida coastline is covered in sun-bleached trees.

A sprawling maze of used books piled from floor to ceiling.

An impressive collection is dedicated to the legendary beast.

The world's largest model of our planetary system.

An 11th-century runestone decorates the halls of Terminal 2 of this Scandinavian travel hub.

A Stockholm metro station is home to an escalator that is not only the longest in Sweden, but among the longest in the world.

This Stockholm light tower can be controlled by anyone with a smartphone.

Celebrating the Swedish ship used in the first Arctic expedition to navigate through the Northeast Passage.

The 19th-century home of Count and Countess von Hallwyl is now a museum.