A submerged village appears when dam levels drop.

This small chapel is built of human bones and decorated with a golden skeleton.

Legacy of the earthquake that nearly wiped Lisbon off the face of the Earth.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

Houses are tucked between, on, and underneath giant boulders.

A former customs station on the border of Germany and the Netherlands.

A beautiful maze marks where three countries meet.

This small town in the Netherlands has no roads but instead, miles of canals and over 100 bridges.

Oldest Museum of the Netherlands is a true cabinet of curiosities.

Home to the world's oldest functioning orrery.

Thousands of well-dressed mummies below a monastery.

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

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

Once overlooking the town, this church now resides on a permanent tilt.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

A church filled with the bones of hundreds of virgins martyrs—or so they say.

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

A madman's personal garden filled with 1,000 sculpted heads.

An underground paleo-Christian burial site composed of the remains of several cemeteries and Basilicas.

The glowing blue Nymphaeum of Emperor Tiberius.

One of seven Jewish catacombs in Rome and one of only two open to the public.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

The Pope’s secret escape route.

A 16th-century horror show built in a lovely Italian garden.