Visit a surreal landscape so otherworldly NASA actually used it to train the Apollo 17 crew.

Partially collapsed lava tube and cave system complete with concert hall, underground pond, and unique albino crabs.

The chefs at El Diablo use heat generated by an active volcano to cook the food.

Stalactites and stalagmites in a beautifully lit cave.

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

Breathtaking and huge 430 year old maps of Italy.

Stone memorial that's said to predict the death of the pope and the site of the Cadaver Synod.

The yawning maw of this pagan visage is said to bite off the hands of liars.

The martyr's wax-enhanced skeletal remains lie preserved in a glass case in the Santa Maria della Vittoria in Rome.

A treasure trove of Renaissance-era funerary art in a Roman church built on top of Nero's grave.

Old Danish castle immortalized in Shakespeare's Hamlet.

The de facto symbol of Copenhagen is this bronze fairytale which cannot seem to keep its head for very long.

Danish tourist destination well known for open stalls where vendors sell marijuana on the street.

Copenhagen's celebrated theme park and gardens.

A favorite with sightseers, this Norwegian funicular provides easy access to a stunning view of Bergen and its environs.

Walk 2,300 feet above the ground on the "Troll's Tongue."

A particularly disconcerting tribute to Irish martyrs.

A living art gallery painted on a canvas of Monterey pine trees.

For one day every month Barcelona's Estació de França transforms into a market for model trains.

One of Europe's largest supercomputers is housed inside of a disused chapel.

The oldest Roman lighthouse still in use.

Giant granite sculptures representing family on the northern coast of Spain.

The remains of an encyclopedic sculpture garden later used as an internment camp.

This Navarrese cave's history of witchcraft and pagan ritual is not just embraced, but recreated each year.