One of the largest ochre quarries in the world, hidden in a limestone landscape.

Figures of unknown origin carved into the surfaces of underground caves.

Beautiful carved tunnels.

Massive puppet-automaton machines created by French artist collective Machines de l’Ile.

Limestone grottoes turns everyday objects into stone.

A garden of massive sculptures sits in Jean Lindard's backyard.

This former limestone quarry is now a subterranean wonderland of grand stonework.

This natural French spring has been turned into a magical grotto by Roman and medieval constructions.

Jean Tinguely's bizarre monster sculpture is hidden deep in a forest.

Abandoned railway line circling the city of Paris.

One of Catholicism's four major basilicas has a series of papal portraits that are said to predict the end of the world.

This legendary city has been a tourist attraction for centuries.

The hallucinogenic center of the ancient world.

Old Danish castle immortalized in Shakespeare's Hamlet.

A surreal statue honoring Prague's favorite literary son.

Steadily reminding Czechia of its past.

The final resting place of soldiers' loyal canine companions.

A statue marks the exact spot where The Boy Who Never Grows Up made his first literary appearance.

360° views of the city plus five floors of optical illusions and hands-on science.

The popularity of Sherlock Holmes led to the creation of his fictional address, turning the orderly London street numbers askew.

17th century streets hidden under Edinburgh were once a breeding ground for the black death.

Famously misunderstood wonder of the ancient world

Former bridge turned into an observation tower.

A small world of mechanical magic and metal merry-go-rounds in a Outsider art Museum.