Inside this McDonald's you can dine on your Big Mac and fries next to a 2,500-year-old Roman wall.

The Pope’s secret escape route.

A forgotten "city of water" underneath the famous Trevi district.

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

Jesus' footprints and the first catacombs in the world.

2300-year-old Roman road connecting the empire.

At the crypt of St. Mary of Eulogies and the Dead you are left alone to ponder mortality among piles of skulls.

The underground sanctuary of a mysterious ancient cult.

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

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

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

The oldest building in Vancouver's Chinatown is now home to one of Canada’s largest contemporary art collections.

This enormous photomural pays homage to Vancouver's infamous history of public activism.

Antiques shop filled with all manner of curious collectibles.

The collection of signage remembers the midcentury pushback against the new neon light.

This Art Deco masterpiece has stood in for some of the most famous buildings in comic book history.

A high point in Vancouver kitsch.

Illegal drag racing two stories beneath Chicago’s streets.

A little-known subterranean street runs under some of the best-known buildings in Chicago's River North.

This whimsical Oz-themed park had a wonderful impact on the surrounding neighborhood.

The burial place of some of Mexico's most prominent residents is full of macabre stories and hidden masonic symbols.

The only castle in North America to ever house European sovereigns.

Gilded heaven for philatelists and architecture freaks, still in full working order despite sitting atop tremulous ground.

The world's largest wooden trestle stretches across this desert canyon in Anza-Borrego Desert State Park.