The solemn exterior conceals an opulent interior of this 17th century church.

An exquisite Baroque church in Vienna's old town.

Abandoned railway line circling the city of Paris.

A series of abstract, silly sculptures represent the works of a great modern classical composer.

This former “ante-chamber to the guillotine” has been refurbished to illustrate the brutal history of French justice.

The spiral staircase hidden inside this giant Parisian column was likely built for Catherine de Medici's astrologer.

Noirish green neon marks the location of one of the oldest private detective agencies in France.

A Parisian exterminator's shop whose storefront displays stuffed rats hanging from traps.

A small marionette collection located within the dark cellars of an 11th-century Austrian castle.

This life-size replica of the Statue of Liberty's flame is also a tribute to Princess Diana by default.

The house that took a plunge into the facade of a museum.

This surreal statue brings a famous French novel about a supernatural cad to arresting life.

Built to give thanks for the passing of a plague epidemic, this cathedral is a one-of-a-kind architectural hybrid.

Apartment complexes built into huge repurposed natural gas tanks.

This former insane asylum now holds a pathological anatomy museum.

This Parisian fountain is a little bit fantasy and a little bit nightclub.

An all-American grocery store in Paris sells U.S. "cuisine" like Pop-Tarts and Heinz ketchup to homesick ex-pats.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

A lone cannonball remains lodged in the walls of the Hotel de Sens as a sober reminder of a revolution.

135 bronze medallions mark a French meridian line which once rivaled the hotshot Greenwich timeline.

The floorboard scrawling of a tragic madman is on public display outside a Paris hospital, much to the dismay of its opponents.

The remaining relics of the patroness of Paris lie in a chapel under a striking double spiral staircase.

An overlooked marble is the only surviving in-place 18th century example of the measurement that changed how we define distance.

An unusual number plate signifies the building's saucy past.