The first skyscraper to include a Ferris wheel built into the facade.

Underground monastery and fortress.

Ancient rock-hewn town that witnessed key events of Georgian history.

A museum glorifying the life of Stalin, located in the city of his birth.

The charmingly disheveled clock tower of Tbilisi's puppet theater.

Luxury hotel turned into a refugee camp, then turned back into a luxury hotel.

The largest of London's subterranean rivers and once a mad, bad center of London life.

A friendly pub with a sordid past in cock fighting.

London's smallest police station is barely the size of a phone booth.

Several plaster noses are hidden in plain sight around London's Soho neighborhood.

A statue of the original Pearly King is hidden in a church's crypt.

This London pub hides a peculiar secret: a recreation of the rooms shared at 221b Baker Street by Sherlock Holmes and Dr. Watson.

Giant, friendly pelicans in Central London, the most unlikely of places.

There’s a secret bunker inside the Brooklyn Bridge, but the city won’t say where.

A beautiful and abandoned New York subway station from 1904, complete with chandelier.

Hidden in plain sight on a pair of Manhattan subway tunnels are a pair of public instruments that sing to each other.

Gang fights don't just happen on the streets, they happen under them too.

Currently housing a corporate bank branch this building at the southern tip of Manhattan was once the gateway to luxury vacationing.

This chapel on a cliff is renowned for its healing powers and was founded on the site of a supposed divine intervention.

A hyper-luxurious, 12,000- square foot home might be buried beneath Queens, still waiting to protect you from nuclear missiles.

Retribution for death of infamous mob boss Franie Yale was a case of mistaken identity.

As telephones become more essential and less stylish one historic Brooklyn building remembers the days when they were a grand celebration of communication.

A ruined mansion hidden in the woods of the Hudson Valley, home of a tragically doomed romance.

Storage warehouse of the rich and famous.