Trek into the depths of the cave where 17,000-year-old paintings exist alongside 400-year-old graffiti.

Some of the smallest works of art in existence.

Historic medieval fortified city in southwest France.

A star-shaped fortress town fort built in the geometric model of the Renaissance utopian city.

Europe's only Temple of Mithras located in a natural cave.

One of the largest caves in the world open to the public.

Martin Bricelj Baraga's monolithic sculpture measures the blueness of the sky, and changes color to match it.

A wonderful museum dedicated to the local straw hat industry.

Castle and secret tunnel withstood a siege until its owner was killed by the Holy Roman Empire, while sitting on the toilet.

A miniature train-ride through Slovenia's largest cave system.

Apparently, Hell has waterfalls in Slovenia.

This was the second largest mercury mine in the world and one of the oldest preserved mine complexes in Europe.

This one-time health resort was used by aristocrats around the world.

In 1888, a resident of Xagħra, Malta, discovered a small underground chamber filled with stalactites and stalagmites when digging a well.

A natural wonder with mythological ties to the local Ainu tradition.

This restaurant serves wood-fired fare served in a natural cave with a live spring.

Britain's tallest megalith towers over the cemetery of a quiet English village.

These abandoned salt flats are now a haven for wildlife.

These sea caves are the source of Xigia Beach's distinct aroma.

Hidden in a secluded Greek cove is a pristine beach marred only by the rusting smuggler's hulk stranded on its shores.

The world's largest collection of preserved trolleybuses.

Half-eaten food on display at an English café.

The mouldering remains of a disgraced British children's icon are hidden in the brush of a public park.

You can crawl inside this atmospheric 5,000-year-old tomb.