This modern arts center is built around a gem of late-Baroque architecture.

A 14th-century fortified keep showcases the masterpieces of an ingenious 20th-century clockmaker.

One of the deepest indoor swimming pools in the world.

Medical history with an amazing, if frighting, collection of wax diseases on display.

Meet the bronze beloved pet to a family of famous peeing statues.

Cozy basement bar sports an inventory of over 2,000 beers.

Climb inside an iron crystal magnified 165 billion times its normal size.

This collection of over 50 murals celebrates Brussels' rich history as the self-proclaimed home of the "comic strip."

This abandoned Belgian fortress is purposefully being left to nature.

A Belgian self-built tower inspired by the Bible and ancient civilizations.

Hiding the longest subterranean river known in the world.

This former Masonic lodge has been transformed into part museum, part bar, all awesome.

A cemetery with goat-horn bedecked gravestones.

A 16th century chapel decorated with bones, skulls, and entire bodies hanging from the wall.

Monasteries on rock pillars, once accessible only by frayed ropes.

Skulls from the plague of 1656 and World War II bombings are united by a cult dedicated to caring for the ancient dead.

These "anatomical machines" are only one of the many strange items in this Italian crypt.

An eerie, little-known Neapolitan museum filled with preserved human remains.

The Neapolitan Cult of the Dead still cares for the skulls at this mini-Fontanelle.

Thousands of well-dressed mummies below a monastery.

Naturally preserved bodies are eerily staged throughout the crypt in varying poses.

Underneath this small church are 15,000 bones, arranged by an obsessive academic.

Hidden beneath the famous St. Peter's Basilica is a veritable city of the dead that may hold the remains of St. Peter himself.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.