In Twickenham sits a small whitewashed castle that inspired Mary Shelley's 'Frankenstein.'

This Prague museum collects brutalist relics and memories from the country's former Soviet rule.

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

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the Harry Potter films.

An underground city of salt.

A uniquely authentic display of traditional Russian culture.

This massive glowering Lenin head gazes out over eastern Siberia.

Replica of mosque destroyed by Russia in the 16th century.

This nostalgic Russian museum is full of USSR cultural artifacts from the 1970s and 80s.

This Russian religious complex is a Frankenstein's chapel that includes influence from almost all the major faiths.

The site of the deadly Triangle Shirtwaist Factory Fire.

Claiming to be the oldest hat store in the world, this historic haberdashery had a hand (and a head) in the creation of the Bowler.

Hidden in a metro shop under a shopping mall, this small museum tells the story of one of the world's largest urban transit systems.

The tallest hotel in Europe.

Moscow's other, lesser known kremlin is a fairytale-like cultural complex modeled after Old Russia.

A century-old hotspot for jazz, frequented by everyone from Charlie Chaplin to Al Capone.

An artsy hidden staircase leads to breathtaking views of San Francisco.

Immortal combat in a Moscow museum.

This building holds the embalmed remains of the leader of the Bolshevik Revolution.

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.

The world's most active stratovolcano is almost always erupting.

A Japanese corporation has turned this small island town into living modern art gallery.

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