A self-built mosaic house and sculpture park.

The largest underground church in Europe.

A cave in southern Italy adorned with thousand-year-old Biblical frescoes existed in obscurity until fairly recently.

Filled with goldfish swimming in a shallow pool of sea water, this ancient crypt is more wishing well than burial site.

A remarkably well preserved tower dating all the way back to the Iron Age.

This picturesque archeological site looks like it was pulled straight from a fantasy novel.

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

This dramatic landscape hidden on the Isle of Skye looks as though you've stepped into the magical realm.

This tiny island featuring 9th-century Viking ruins is only accessible at low tide.

Do these monsters look familiar? The gargoyles on this church are all from pop culture.

A huge Megalithic chamber tomb located behind a cafe.

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

Beautiful carved tunnels.

A bike train runs along a disused railway line through the tranquil French countryside.

A part of the world's largest marsh seems to be growing bright red Martian grass.

An architectural marvel that spans the Arda River, and has stories of a haunted past.

Ruins of a German Castle on top of a towering stone pillar.

This jaw-dropping 19th-century bridge uses its reflection to form what appears to be a perfect circle.

A local tree surgeon has created a whimsical walk full of carved tree stumps near Scotland's Loch Lomond.

A remote hilltop covered in giant monoliths haunts the Brittany countryside.

An isolated 17th-century chapel on a remarkable site once dedicated to Celtic sun worship.

Colin Stokes "got a bit carried away" and built a castle that looks like something out of Tolkien.

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

This stunning natural double arch, the largest in the Alps, went undiscovered until 2005.