Largest necropolis in the Mediterranean.

This military mausoleum captures the solemn grandeur that most memorials only aspire to.

Water and windows define this defensive Italian well.

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

This gallery commissioned by Cardinal Spada is known for its magnificent optical illusion.

This is the oldest Roman-made bridge in the city still existing in its original state.

The burial place of an obscure North African saint was turned into a macabre body preservation factory for the 17th-century Neapolitan elite.

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

A domed disco abandoned since the '70s now attracts artists and explorers under its unique roof.

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

An Italian ghost town that fought obscurity, until a mysterious illness brought it to its knees.

A complex, nine-layer maze on the grounds of a Venetian doge's playground.

This real life asylum of horrors is now an abandoned ruin that hides the unbreakable code to one patient's insanity.

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

This quaint Italian town keeps losing ground as the sides of its plateau slowly erode.

This beautiful park on the outskirts of Rome protects the ruins of two colossal ancient aqueducts.

Thousands of well-dressed mummies below a monastery.

The engineering wonder and pleasure dome of a much-maligned emperor still holds undiscovered secrets.

At the crypt of St. Mary of Eulogies and the Dead you are left alone to ponder mortality among piles of skulls.

A spherical "micro-nation" in the heart of Vienna.

The inverted pyramid design of this station stands out amid Bratislava's urban landscape.

An unmistakable facial pareidolia in the Julian Alps also includes a fantastic tale.

This former railway facility is the oldest in Slovenia, and now houses a museum showcasing the history of steam locomotives.

Apparently, Hell has waterfalls in Slovenia.