The mastermind behind this palatial hotel perished on the Titanic weeks before its grand opening.

This inexpensive lodging house was once a prison notorious for its inhumane practices.

Louise Bourgeois' 30-foot-tall steel spider sculpture.

This elaborate towering structure was once famed for its revolutionary height.

The first American department store, and home to the largest operating musical instrument in the world.

Yo, Adrian!

This charming colonial alleyway is one of the oldest continuously used residential streets in the U.S.

Huge masonic hall in Philadelphia with lavishly themed rooms.

This extraordinary Depression-era expenditure was modeled after a postcard of a Mediterranean hotel.

Macabre astrological automaton clock dating to the late 1400s.

Paris' linguistic guide to the international language of, yes, love.

This 17th-century street hidden beneath Edinburgh was once a breeding ground for the black death.

A toxic ghost town sitting atop a massive coal fire.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

The world’s oldest and biggest bookstore stocking only mystery, crime fiction, espionage, and thrillers.

A layered tribute to the work of mosaicist Isaiah Zagar.

The intricate stonework of Machu Picchu serves as a testament to Incan engineers.

Elevated freight railway turned wildly successful urban park.

The fairy tale castle of the “fairy-tale king,” this was also the inspiration for Disney’s “Sleeping Beauty.”

The legendary building that needed ghostly approval before being built.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.

Amid the bustle and noise of the Financial District hides a secluded garden oasis above the city streets.

The world’s first penitentiary, meant to be humane, drove men insane.