Hidden beneath the streets of London is a secret subway that only carried mail.

A 300-year-old tea shop that brought tea to the English people, not to mention the Queen herself.

Its collection includes a broad array of social, geographic, graphic design, and political history.

The Metropolitan Police refurbished the blue box (perhaps not coincidentally) the same year "Doctor Who" returned to TV screens.

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

Home to Alan Turing, the cracking of the Enigma code, and Captain Ridley's shooting party.

A cluster of historic bathhouses built on the famed hot springs that gave the Georgian capital its name.

A cylinder monument with a spectacular vista commemorates a friendship that some say never existed.

Unusual building appears to be haphazardly built from randomly piled bricks.

Take respite inside this jaw-dropping church while climbing the volcano where Georgia's Prometheus was once chained.

At this rare mosque in Tbilisi, Sunni and Shia Muslims pray side by side.

Tower with a double-helix spiral, adorned with letters of the Georgian alphabet.

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

A literally moving statue of stacked metal giants just continually trying (and failing) to find love.

A grassroots community effort in the 1970s led to the creation of this beautiful garden full of delightfully whimsical exhibits.

Huge stairway leads to this massive gallery.

Destruction from Armenia's 1988 earthquake inspired an artist's sculptures of scrap metal.

This ancient monastery complex was transformed from an island to a peninsula when the lake was partially drained.

This Armenian monastery was carved out of cliffs and named after the spear used to stab Jesus.

A geological oddity topped with a 2,000-year-old pagan temple.

This museum was invented in a novel before being made real by the author.

A gorgeous, Gaudí-esque stairway constructed in the city of Istanbul by a prominent Jewish family.

This crucial gathering spot along the "hippie trail" still displays old notes between traveling beatniks and backpackers.

A marvel of Byzantine engineering under the streets of Istanbul.