The Beaux-Arts aquarium boasts a vast collection of saltwater and freshwater fish on an island in the Detroit River.

The glowing blue Nymphaeum of Emperor Tiberius.

17th century streets hidden under Edinburgh were once a breeding ground for the black death.

The hallucinogenic center of the ancient world.

A treasure trove of artifacts, books, and artwork from the "golden age" of exploration.

Jesus' footprints and the first catacombs in the world.

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."

The underground sanctuary of a mysterious ancient cult.

Eyam took steps to quarantine themselves and keep the plague from spreading.

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

An open air haven for tropical monkeys in the damp moors of the English country.

A spectacular cave and a beguiling lake.

The palace of the King of Kings, burned by Alexander the Great.

Giant marble phalluses on the sacred island of antiquity.

The maritime museum that boasts the largest nautical library in the western hemisphere.

The largest prehistoric ruins south of the Sahara, once a powerful center of international trade.

A Parisian cemetery where the elite and artistic are interred beneath an eccentric collection of tombs.

Home to three historic ships from the age of Vikings.

The John Snow Memorial marks the epicenter of London's 1854 cholera epidemic.

Science fiction's grandfather has a fittingly marvelous tomb.

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

This single room has survived the centuries with almost no deterioration.

Perfectly preserved ancient monastery in an impossibly dramatic location on a rocky island in the Atlantic.