This bronze boar's snout has been rubbed to a golden sheen by visitors seeking good fortune.

The doodles of a genius line the walls of a secret room under the Medici Chapel, where they were hidden for nearly 500 years.

This Roman arch marks the location of an ancient gate at one of the Seven Hills of Rome.

Hidden beneath the famous St. Peter's Basilica is a veritable city of the dead that may hold the remains of St. Peter himself.

The yawning maw of this pagan visage is said to bite off the hands of liars.

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

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

Possibly the oldest church in Barcelona, this basilica has its pagan and Christian mythologies all mixed up.

A vista of the city and sea from atop the little-known viewing deck on an unassuming Columbus statue.

Turntable anonymously received orphans, alms, and groceries.

An unusual stroll through gentlemen's erotica demonstrates that pornography is timeless.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

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

There's a piece of New York City transportation history hidden in plain sight at a Manhattan subway stop.

This historic address is home to the beloved ball and is an almost totally empty building among the most expensive real estate in the world.

A bit of retro transportation flair preserved in the world's largest department store.

A pedestrian island in the middle of world-famous Times Square emits a strange (and purposeful) humming noise.

Tucked in the back of this amazing antique store is an important piece of medical history.

Once at the center of U.S. finance, the historic Trading Room was meticulously recreated piece by piece and rebuilt in the Art Institute.

Fragments of architectural wonders from around the globe are embedded in the newspaper building's walls.

The unluckiest U-boat in the entire German fleet is now on display in a Chicago museum.

This $3 million model train takes you through Chicago, Seattle, and the thousands of miles in between.

Each of these gorgeous, intricately decorated rooms is painstakingly crafted to the scale of 1 inch: 1 foot.