Yugoslavia's biggest underground airport lies in ruins.

An eerie, derelict amusement park in Berlin.

A dilapidated psychiatric facility on the outskirts of Milan where electroconvulsive therapy was developed and Napoleon once lived.

A space dedicated to contemporary art and culture, co-chaired by fashion icon Miuccia Prada.

This camera store in Milan holds one of Europe’s largest collections of luxury-antique cameras.

An ossuary built in 1210 to collect bones from the Ospedale Maggiore of Milan.

Just across from the "Last Supper" painting is the famous painter's vineyard, a gift received for creating the masterpiece.

Spiral alpine structure provides an alternative experience of viewing the Matterhorn.

A fairytale island floats in the middle of Italy's little-known Lake Orta.

This Italian pyramid is said to hold the mingled remains of the dead from both sides of the Battle of Novara.

This brightly-colored chapel is a contemporary jewel standing in the middle of a La Morra vineyard.

A formerly opulent Italian village is now a crumbling ghost town that no one really knows what to do with.

An abandoned bell tower in the middle of nowhere is the last testimony of a forgotten medieval village.

Europe's simulation of the Martian surface uses soil from Mount Vesuvius.

A Milanese café entirely designed by the American director Wes Anderson.

A completely underwater art museum sends a stark message about humans' impact on the environment.

This beautifully verdant lagoon is tucked below a massive volcano in a crater atop a black pebble beach.

Remnants of a Victorian garden feature sitting in public woodland.

Wedged between two buildings at the Great Ormond Street Hospital is this secret music installation.

The world's first underground farm is in a World War II bomb shelter beneath the streets of London.

Winding paths and ramshackle mausoleums in the oldest "park cemetery" in London.

An easily overlooked stretch of ornate window fronts and gaslight lamps that could be right from the pages of Dickens.

London's creepiest cemetery was once the site of dueling magicians and mobs of stake-carrying vampire hunters.

Famed for its pie, this eatery has a hidden tunnel that allowed Catholics to secretly walk to church during the Reformation.