Alleyway plaque commemorating the death of a fictional character in The Maltese Falcon, not far from the author's home.

Giant WWII fortresses that fired 8,000 rounds a minute, now home to thousands of pigeons.

Where commuters walk through remnants of an ancient Greek necropolis.

A popular tourist cave with a dark past.

These "bridges" help confused bats cross the road.

Five mile wide circular ring of rock in the Russian Far East is a curious geological oddity.

Railroad came. People came. Railroad left. Town died.

Curious rock formations in a tiny Kansas state park.

19th-century operating theatre in which the use of ether was first demonstrated - plus, a skeleton and a mummy!

Architectureal fantasy quarter of Rome.

Profile of a sleeping person 4km long in 250m high cliffs.

The largest earthwork effigy in the world.

This mill on Lake Erie appears to shrink as a viewer approaches thanks to an optical illusion.

With over 100 jam-packed rooms to explore plus elaborate tea services and events, the Mansion on O Street is a hidden treasure.

An old saloon in the West filled with history, and according to some, a few dozen ghosts.

Pyramid shaped monument with a tall tale attached.

Spain's stunning solar energy plant.

The biggest and deepest Cold War bunker open to the public can be found in southeast England.

Oldest Museum of the Netherlands is a true cabinet of curiosities.

The original film set of Luke Skywalker's Tatooine home from the 'Star Wars' trilogy.

Hundreds of wooden coffins dangle from cliffs and caves in the Philippines.

One part antique store, one part curiosities hodge-podge.

A nursery specializing in strange and beautiful succulents and cacti.

Russian Orthodox church built on an Antarctic island.