One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

Home to items never before seen by the public.

The ancient dwellings of the Puebloans, located in the cliffs of majestic mesas.

One of the Seven Wonders of the Modern World holds the world's tallest metal staircase.

The second oldest continuously operating bar in Louisiana.

San Francisco's newly reopened hands-on science museum.

Four glass boxes hover over 1,000 feet in the air to give visitors an unparalleled view of Chicago.

The final resting place of New Orleans' most famous voodoo priestess.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

A walk through the historic city center, under the streets of Seattle.

France's most famous cemetery, with some of its most curious tombs.

This historic address is home to the beloved ball and is an almost totally empty building among the most expensive real estate in the world.

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

A wall of chewing gum moonlights as collective art.

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

Elevated freight railway turned wildly successful urban park.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

The celebrated eyesore created by starry-eyed sweethearts.

A former waterfront market is now in the center of town due to some interesting Boston engineering.

Macabre astrological automaton clock dating to the late 1400s.

Six beautiful wooden giants are hidden around Copenhagen.

A collection of Witchcraft artifacts and occult paraphernalia started by the leader of the Long Island Coven.

The Pennsylvania landscape depicted by a quarter mile of mosaics made from used road signs.

Daredevil repair workers can worm their way out the access hatch, loop ropes over the apex and rappel down the monument.