This newly renovated Soviet-era outdoor exhibition center is bigger than the principality of Monaco.

Gargantuan home of Russian science.

Moscow's imposing monument to the Space Age.

Moscow's most popular cemetery includes the graves of numerous cosmonauts.

The gorgeous entrances into the city's underbelly look more like grand halls than subway stops.

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

An unusual round church in London with a Templar past.

The quaint little store that is said to have inspired a famous Dickens novel was only given its name after the book was released.

One part local history, 99 parts gruesome haunted house.

The popularity of Sherlock Holmes led to the creation of his fictional address, turning the orderly London street numbers askew.

The slender brass strip in Prague's Old Town Square was used to tell time from 1652 to 1918.

A turn of the century building boasting some of the most beautiful art nouveau architecture in Prague.

The first museum in the world devoted to sexual gadgetry.

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

The hidden lair of an alchemist rediscovered in a 2002 flood.

Macabre astrological automaton clock dating to the late 1400s.

Two stunning 17th-century libraries and a cabinet of curiosities.

Constructed in the 1920s, this former pencil factory is now an office building.

The largest crypt ever constructed in France was built in the 11th century on an ancient Druid sacred site.

The famous winding walk at Chartres is surrounded in mystery and myth.

A scandalous Art Nouveau collaboration that set Paris all atwitter at the turn of the century.

Unscathed for almost 2,000 years, the best preserved Roman triumphal arch is in a small southern Italian city.

The tradition of open-air secondhand and antiquarian bookselling in Paris dates back to the Renaissance.

The water-powered carriages are long gone, but for over a century this funicular railway has been the fastest route to the highest point in Paris.