Macabre astrological automaton clock dating to the late 1400s.

The fairy tale castle of the "fairy-tale king."

A peculiar mansion built by the troubled heir to the Winchester Rifle Company fortune.

The body of at least one victim of a construction accident was left behind in the collapsed pylon, buried under tons of concrete.

"the sweltering inhabitants of Charleston and New Orleans, of Madras and Bombay and Calcutta, drink at my well . . . The pure Walden water is mingled with the sacred water of the Ganges."

South Carolina's last remaining slavery auction house is now a museum devoted to its own tragic history.

A heroic pigeon that, through a barrage of gunfire, delivered a message that saved over 100 lives in World War I.

The "lovely red Vega" of the legendary record-settling pilot.

The remains of Martha, the last known passenger pigeon, serve as a tool to educate about conservation.

A monument in Washington D.C. marks the spot from which all other roads were supposed to stem.

At Washington's Dulles Airport is a satellite museum (no pun intended) with three quarters of a million square feet of aircraft history.

The "Prussian Versailles" that is as glorious today as when it was built.

At 207 feet, one of the world's longest continuous escalators.

Dress up like a miner and take a slide into the disco-lit depths of this once foundational salt mine.

Soaring over 6,000 feet in the Bavarian Alps, this beer garden was once Hitler's 50th birthday present.

Jesus' footprints and the first catacombs in the world.

2300-year-old Roman road connecting the empire.

Italian cave with exceptional acoustics and an unsavory history.

Send a postcard while vacationing with Satan.

Two geological phenomena in one precarious locale: a towering stone window, and a deep blue void.

Two gravestones clasp hands over the religious divide.

This modern French ossuary contains the jumbled bones of 130,000 WWI soldiers.

This museum preserves the hand-dug tunnel that kept Sarajevo afloat during the Serbian siege.

1513 Turkish world map, full of European state secrets and snarky commentary.