Cavernous opening completely encased in Karst limestone.

The only university zoological museum in London houses extinct animals, bizarre natural history specimens, and a Micrarium of microscopic creatures.

This shop and gallery is a modern-day cabinet of curiosities, unassumingly positioned along an urban thoroughfare.

Housed in an old church, this hunting museum holds a collection of mythical bird-rabbit creatures.

A wunderkammer of mysterious objects and stories.

A tour of underground Berlin takes you through WWII air raid shelters and tunnels used to smuggle people out of East Germany.

A haunting collection of the vanished and disappearing natural world.

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

Notorious artist squat renovated into legal studios.

The macabre collection of Jacques Sirgent, an expert scholar on the undead and all of their trappings.

A little-known cafe in an old copper bridge tower with 360-degree views of the harbor.

An abandoned railroad tunnel is now filled with bioluminescent bugs.

Once the path of a railway tunnel, now home to thousands of glowing insects.

This dramatic sea spire is home to the world's rarest insect and is part of the lost continent of Zealandia.

Australian Lake set aglow by Noctiluca Scintillans.

An Australian lake whose pink hue defies scientific explanation.