The last masonry skyscraper ever built reveals a transitional moment in architectural history.

Opened in 1956, the first modern indoor shopping mall in the world was inspired by the shopping arcades found in European cities.

Literally a million fascinating cartographic artifacts are held in this sprawling university collection.

This mansion was made famous by its colorful cast of owners and location along the Sante Fe Trail.

A rugged lava field dotted with molds of the ancient pines that were growing when the volcano erupted.

The longest continuous lava tube in Oregon.

On the Oregon coast there is a natural hole that seems to be draining the sea.

Largest magic museum in the United States with more than half a million pieces of memorabilia.

This futuristically sylvan church is a glass-enclosed marvel of modern architecture.

An abandoned early-20th-century boomtown sits within the Calico Rock city limits.

Curious cave that stays a cool 56 degrees all year long.

The final remnant of the Arkansas zinc industry is this historically protected ghost town.

Once an ambitious nature spa, these forest ruins now provide a serene monument to failure.

House built with over 60,000 glass bottles.

This museum remembers an apocalyptic cult that became more famous for baseball than religious radicalism.

A perfect circle of twenty-four mysterious holes dates back to prehistoric time.

Beside some power panels, a plaque celebrates the history of an alternate world.

Mysterious ancient boulder carved with petroglyphs in the mountains of Western North Carolina.

A mysterious monument meant to be a guide into "an Age of Reason" was destroyed after an apparent bombing.

A deeply beautiful 15th-century stepwell with a tragic story.

Enormous lake at the bottom of a unique cave system.

An art instillation for the sake of "raising vibrations."

For two weeks every June, fireflies in the Smoky Mountains perform an astonishing light show.

Crumbling ruins mark the site of a couple's grisly murder in the woods.