In the world's oldest university is a stunning 17th century anatomical theater carved from spruce.

This ancient Visigothic church might hide an ancient treasure.

The fragmented remains of a massive public bath connected to the city's water supply.

For decades, Puerta del Sol has been illuminated by a giant, guitar-wielding bottle of sherry.

This small and often-overlooked museum holds some of Spain's finest artistic treasures.

This lucky bronze frog was gifted to Madrid by a casino.

This macabre masterpiece of a mural is one of Francisco Goya's "Black Paintings."

A lush indoor jungle fills this bustling Madrid transportation hub.

Controversial tribute to the heavyweight champion boxer who grew up in Detroit.

These enduring murals depicting a distinctly Marxist tribute to capitalism could not even be defeated by McCarthyism.

Cryptic messages embedded in the New York City sidewalk.

Sniff the Titan Arum's rotting flesh.

The "Seinfeld" diner.

Elevated freight railway turned wildly successful urban park.

A blend of art, antiquities, and Americana fill this museum, surrounded by whimsical, enchanting gardens.

Architecture lovers won’t stop touching the National Gallery's 19.5 degree marble prow.

Before Nixon, "watergate" meant canals.

This beloved Baltimore spot features caged dolls, a giant Pez collection, and many, many mannequins.

A museum dedicated to exhibiting remarkable outsider art.

It's not hard to see why the historic Peabody Conservatory of Music's library has been described as a "cathedral of books."

Oldest unrestored plantation house in America that is open to the public.

It houses the remains of a 17th-century version of the Titanic.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

Fortified medieval tower house with lovely roof garden.