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

Ruined 11th century abbey built by King David I in Edinburgh, Scotland.

The most loyal of little dogs, or a Victorian era publicity stunt?

There are plenty of wonderful panoramic vistas in Edinburgh, but not many are hidden smack in the middle of the Old Town.

"Stairs of the Turks", a chalky white cliff eroded conveniently into stairs, allowing for easy pillaging.

Catacombs turned marketplace.

Artists and musicians now rule over this former rail station.

Mary Kelly was last seen here before she was murdered by Jack the Ripper.

Architectural monsters are devouring this palace's every door and window.

Geothermal waterfalls in Tuscany.

This massive blockhead sculpture hides an entire library.

A fake medieval village in the middle of Turin.

When this funny little building went up in the 19th century, most people thought it would simply fall over.

Two very green residential towers cleaning the air in one of Europe's most polluted cities.

A whale rib was used to advertise the store by the arch that offered exotic goods from far away.

Pilgrimage site for star-crossed lovers.

The bomb-ravaged remains of of a colossal Neptune.

A lover's walk between hilltop towns, decorated with graffiti love notes.

Five candy-colored villages on the Italian Riviera.

A small window on Via Piella offers a lovely and rare peek at Bologna's lost canals.

Legend has it this fountain built to symbolize the Pope’s power hides a strange secret concerning Neptune's manliness.

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

This picturesque horseshoe weir was first built in the 1600s to prevent flooding in the town of Bath.

Used as an example in one of the first dictionary entries for "museum" in 1706.