A small part of lower Manhattan is actually made from a bit of England.

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

A beautiful and abandoned New York subway station from 1904, complete with chandelier.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

Enter the cabin of a life-sized Hindenburg replica.

A small man-controlled waterfall powers an Art Nouveau elevator and is accessed via narrow gauge, solar-powered tramway.

Ruins of a German Castle on top of a towering stone pillar.

After a nearly successful attempt on Hitler's life, the conspirators met their fate in the courtyard of this Berlin building.

This classic restaurant features a gorgeous mirror-clad room.

Blitzkrieg bop your way through Berlin's Ramones Museum.

Berlin's natural history museum houses the world's largest mounted dinosaur and the late beloved polar bear Knut.

Home to 10,000 medical specimens including the remains of Rudolf Virchow's extensive collection of pathological specimens.

2300-year-old Roman road connecting the empire.

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

Museum dedicated to literary greats of the Romantic Period is also the home in which Keats met his untimely end.

Rome's semi-secret peephole vista is also a former Crusader stronghold.

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

A mysterious chasm in the heart of the ancient Roman Forum, the Lacus Curtius was once believed to be a gateway to hell.