A railroad tunnel that, upon its completion, was considered one of the engineering marvels of the modern world.

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

This ritzy Italian market is built around a statue of an unforgiven heretic who was burned for his belief in an endless universe.

2300-year-old Roman road connecting the empire.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

This hidden Art Nouveau courtyard is an opulent feast for the eyes.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

Staves, storm-calling, and of course, necropants.

The fountain marks the area where hundreds of accused witches were burned at the stake.

Railways may have forged this quintet of lovely tunnels, but now they are open to hikers.

Off of the Crawfordville Highway in Florida, nature is taking back this decrepit row of Ford trucks.

A hidden beach at the end of a tunnel of mangrove trees.

The ruins of this antebellum sugar plantation are the end result of a Seminole attack during the Florida Wars of 1836.

Stay in a room with a view... of the bottom of the ocean.

The former home of the Nobel Prize-winning American writer is now home to dozens of six-toed cats.

St Bernard de Clairvaux Episcopal Church, better known as one of the oldest European buildings in the Western Hemisphere.

These remote Florida islands have a history of sea turtles and sunken treasures, and one of the world's largest coastal brick fortresses.

This early version of the guillotine was used to execute the man responsible for its construction.

This allegedly haunted 16th-century tower house-turned-museum exhibits thousands of spectacular objects.

This small museum in a 17th-century building honors three iconic Scottish writers.

Remnants of the 16th-century defensive wall still stand unassumingly within Edinburgh.

The 16th-century church has the only stained glass windows that survived the Scottish Reformation intact.

A secret garden in a picturesque Edinburgh village has inspired artists for centuries.