Bell tower juts out from a village buried under a lake.

People have been living in the cave houses on this Italian hillside since the Neolithic era.

The sinister ruins of one of the worst dam failures of the 20th century lie in this astonishing alpine setting.

This abandoned Brutalist treehouse is a hidden architectural relic.

A sinister pyramid in the Frari contains the heart of the famous neoclassical sculptor.

Sitting on an Italian hilltop is this surreal fortress built by the mad inventor of electrohomeopathy.

A large grotto built in the 16th century amidst Florence's famous Boboli gardens.

Renaissance villa and gardens complete with a tormented colossus.

This Venice bookstore has resigned itself to constant flooding by keeping its books in bathtubs and boats.

A 16th-century horror show built in a lovely Italian garden.

A 14th century bridge built as a fortress, where the devil lurks on one of its towers.

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

A self-built mosaic house and sculpture park.

A medieval church with largest and oldest collection of Renaissance frescoes in France.

The mental institution where Van Gogh created some of his most famous work now allows guests to walk in the artist's footsteps.

One of the greatest maze designer’s greatest mazes.

Sacked by Vikings, blessed by William the Conqueror, dealt a fatal blow during the French Revolution—these ruins have seen it all.

The man who introduced reinforced concrete to the world demonstrated its genius by using it to build his own house.

A beautiful lighthouse with as many steps as days in the year, as many windows as weeks, and as many levels as months.

A total of 22 tiny bridges cross this canal of the Yvette River, forming a unique trail.

Experience architect Le Corbusier's modernist design for living in the home he designed for himself.

A castle-like sea fort from the 17th century is now a museum to oyster farming.

An image of the legendary saint stands in the shadow of a cathedral she liberated.

Trek up this glacier before it disappears.