Despite attempts by local police to discourage it, Beatles-inspired graffiti has been a means for artists to air grievances for decades.

A series of playful yellow penguins share a serious message about the environment.

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

A 400-year-old mummified arm dangles from the ceiling of St. James the Greater, serving as a warning to thieves.

Macabre astrological automaton clock dating to the late 1400s.

What looks like a suicide in progress is actually a statue of Sigmund Freud.

A mocking tribute to the past and modern leadership of Prague.

This spooky statue sits outside a famous Prague theater.

The internal railway of one of the biggest steel plants in America has been transformed into a linear park with unique industrial views.

The famous bell was secreted away and hidden in a church in Allentown during the British occupation of Philadelphia.

America's oldest drive-in movie theater has been in continuous operation since 1934.

The key to turning shifting dunes into the green oasis of Golden Gate Park.

Once the largest windmill outside of Holland, with enormous 114 foot sails.

San Francisco's urban bison herd has persisted in the face of extinction, development, and disease.

The remains of a ruined mansion memorialize the 1906 earthquake.

Carnivorous plants, medieval aphrodisiacs, and the largest original wood structure glass conservatory in the western hemisphere.

San Franciscans leave gifts and messages for the magical beings that live behind the tiny, mysterious door installed on a tree in Golden Gate Park.

Relics of the 1894 Midwinter Exposition continue to delight visitors today.

Art in the form of a winding, man made crack in stone.

A masterpiece in Golden Gate Park by virtue of the artist’s debt.

A garden oasis filled with flowers mentioned in the works of William Shakespeare.

An elaborate gift from Claus Spreckels is now a piece of San Francisco history.

Olfactory delights in San Francisco's Botanical Gardens.

This concrete tangle of square pipes has stood as a proud thorn in the city's side since the '70s.