Where once there was a train station bathroom, there is now this German burger joint.

This World War II bunker now survives as a documentation of the Nazi regime and war crimes.

A tour of underground Berlin takes you through WWII air raid shelters and tunnels used to smuggle people out of East Germany.

This futuristic German spa allows visitors to float in a pool of salt water while zoning out to underwater techno.

Started as a kitchen garden, now the second largest botanical garden in the world.

An eerie, derelict amusement park in Berlin.

The largest free-standing aquarium in the world resides in a hotel lobby in Berlin.

A surreal museum of extraordinary industrial objects.

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

Filled with goldfish swimming in a shallow pool of sea water, this ancient crypt is more wishing well than burial site.

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

A sunken idol welcomes parishioners to Davy Jones' Locker.

Hidden in an Italian forest is a completely homemade amusement park that has taken a lifetime to create.

The glowing blue Nymphaeum of Emperor Tiberius.

Geothermal waterfalls in Tuscany.

Stalactites and stalagmites in a beautifully lit cave.

Pompeii's less famous neighbor is still revealing her secrets.

Thousands of well-dressed mummies below a monastery.

A submerged archeological park still holds the wonders of a Roman Sodom.

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

Barcelona's historic 19th-century sewers, whose foundations were laid in medieval times, are open to the public for exploring.

Week-long block party becomes a competition for the best decorated street.

Gaze upon chocolate sculptures depicting everything from chariot races to Gaudí's famous church at this shrine to sweets.

Visit the WWII bunker where the British won the battle for the skies.