Where condemned pirates met their grisly end at the gallows on the River Thames.

This hydraulic power system in London was, at one time, seen as a rival to electricity and the last of its kind to shut down.

This mysterious pyramid is said to be part of a complex web of occult and Freemason symbols.

This medieval cathedral houses stained-glass windows featuring saints and pretzels.

A set of 13th and 14th century standardized bread measures.

A stonemason's hilarious revenge came in the form of this peculiarly positioned gargoyle.

Local legend of a lurking canal crocodile takes on a life of its own with this sculpture.

Located in a heritage building, this Mickey D's is missing its Golden Arches.

These paved rills bring freshwater into Altstadt and could spell wedding bells for whoever stumbles into the waters.

This Late Gothic building that once housed Erasmus is now known as the filming location of "Suspiria."

A pink sandstone column once used in ancient times to measure one's belly after a night of debauchery.

Explore this medieval cathedral by trying to spot all the malevolent monsters hiding in its beautifully colored windows.

Visitors dating back to the 1600s carved their marks in the stones of the iconic tower.

There has been an astronomical clock on this spot since the 14th century.

Montmartre's sole surviving windmill became an iconic landmark for 19th-century painters, artists, and bohemians.

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.

Paris' linguistic guide to the international language of, yes, love.

This modest marker near Notre Dame identifies the very center of Paris.

This demon atop the Notre-Dame de Paris looks utterly bored.

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

The narrowest street in Paris.

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

This 400-year-old tree is actually an immigrant from North America.

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