This abandoned subway station beneath the Waldorf-Astoria hotel is allegedly used to secretly transport presidents.

Remants of foundations, streets, and streetcar tracks inhabit the cliffs where a landslide occurred in 1929.

A collection of oddities including Dr. Kevorkian's suicide device, the Thanatron.

A snapshot of the city's fascinating voodoo culture.

An iconic 1960s theater with a Buckminster Fuller-style geodesic dome.

This Las Vegas casino boasts one of only three spiral escalators in the United States—an engineering wonder.

The arch that celebrated the completion of the Lincoln and Victory highways.

These markers are used to determine the ground stability of the Strip.

A tiny slice shop hides down an unmarked hallway in a Las Vegas casino.

This historic estate on the east shore of Lake Tahoe was home to an eccentric millionaire (and his pet elephant, Mingo).

A breathtaking 19th-century trail overlooks Lake Tahoe.

An enormous illuminated figure dances on the Las Vegas strip.

A giant open-air sculpture made of over 200 full-sized boats.

These banned cigarette vending machines now sell little pieces of pocket-sized art.

The farm where one of America's most famous folk artists created her paintings.

The building that inspired Shirley Jackson's "The Haunting of Hill House."

The underground sanctuary of a mysterious ancient cult.

Famously misunderstood wonder of the ancient world

Near the former site of numerous witch burnings, this lavish Edinburgh mainstay pays homage to Scotland's brutal history.

This coffee shop lies hidden beneath a historic church.

A winding path built in secret on the edge of the continent.

Rome’s legendary peephole vista is also a former Crusader stronghold.

This massive stained-glass masterpiece is thought to be the largest Tiffany dome in existence.

Eighty million natural history specimens call this gargantuan museum home.