This Pennsylvania cave holds evidence of the oldest known inhabitants of North America.

This shrine to McDonalds' most iconic sandwich holds a 14-foot tall burger.

The United States’s oldest funicular railway glides up and down a steep Pittsburgh street.

This historic Pittsburgh tennis complex is a rare example of natural red clay courts.

Meet your friends, marry your true love, or tell your enemies to kiss your butt under this historic Pittsburgh timepiece.

This spot memorializes one of the greatest plays in NFL history, unless you happen to be a Raiders fan.

The Master of Magnetism dominates the walls of a scrap metal yard to keep graffiti artists at bay.

A restored Pittsburgh house of God has been converted to a marvelous house of suds.

An imposing pair of sphinxes stand guard outside this Egyptian Revival tomb.

Could it have picked a better place to land?

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

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

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

This 18th-century sundial was designed to calculate the date of Easter each year.

A museum dedicated to one of Paris’s most famous residents, tucked into a corner of one of the city’s most famous squares.

This emotive sculpture was originally created for the 1878 World's Fair.

The Argonaute submarine was the French navy's pride and joy in the 1950's.

In this Parisian garden's grotesque former life as a zoo it fed exotic animals to the bourgeois and put humans on exhibit.

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

Remains of Roman amphitheater hidden in a sleepy quarter of Paris.

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

Natural history museum celebrating biodiversity with a parade of taxidermy animals.

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

The curious underground history of keeping Paris clean.