A 300-yard long natural tunnel runs through a ridge deep in the Appalachian Mountains.

An enormous warehouse filled with parade floats collected from over 50 years of patriotic celebrations.

Outsider art meets paleontology at this roadside reptile repository.

Nine of the very few concrete ships ever made in the U.S. are beautifully decaying off a Virginia pier.

A secretive collection featuring objects that were designed specifically for U.S. intelligence operations.

This tiny New Jersey village has lived many lives but seems determined to remain a ghost town.

This mystical orb covered in strange symbols is thought to have been used in ancient Greek magical rituals.

This small 16th-century church in Athens is almost entirely surrounded by a modern building.

An ancient octagonal weather station named for the eight Greek gods of wind.

Miraculous tree that seems to sprout out of solid rock.

One of the smallest towns in the United States.

A unique attraction and museum dedicated to exploring iconic roadside structures.

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

This former Roman Catholic Church still contains the embalmed hearts and organs of 22 popes.

The skull of the patron saint of lovers lies in the Basilica di Santa Maria in Cosmedin—maybe.

Rome's semi-secret peephole vista is also a former Crusader stronghold.

This hill made entirely of ancient Roman jars was simply a garbage dump to the people of the time.

2300-year-old Roman road connecting the empire.

Jesus' footprints and the first catacombs in the world.

The second-highest village in Lazio has attracted artists for 400 years and is now a spectacular open-air art gallery.

Romans built the world's tallest artificial waterfall in 271 BC.

Small on the outside, big on the inside, this church is an astonishing act of visual deception.

This giant middle finger statue sends an unambiguous message to Italy's bankers.

"The prettiest love letters in the world" ... or so said Lord Byron.