Small plaque marks the spot, but the true center is located about half a mile away on a private pig farm.

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

See massive fossils that are over 200 million years old in northeastern Arizona.

The marker offers a rare chance to be in four U.S. states at once, though there's some controversy over its geographic accuracy.

"We Seceded Where Others Failed."

The world's longest known cave system.

This prehistoric sinkhole lured exclusively male mammoths to their death, much to the delight of science.

The granddaddy of all tourist traps, built on ice water, jackalopes, and a giant dinosaur.

The world's largest mountain carving could fit all of Mount Rushmore inside it many times over.

This Yellowstone geyser may not shoot as high as the nearby Old Faithful, but it erupts for considerably longer.

Native Americans built this circle of stones, which was used to predict astronomical events.

The first declared National Monument in the United States.

The spot in the Mile-High City that's exactly 5,280 feet above sea level (at least for now).

One of the greatest heroes of the Titanic tragedy came from humble beginnings to this beautiful home.

Despite being one of the most photographed vistas in the Rockies these twin peaks are rightfully known as the "Deadly Bells."

One woman's UFO-themed campground, complete with self-built energy vortexes, UFO-themed weddings, and magic bushes.

When ecosystems collide in the arid Southwest.

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

The largest stone circle in the world has ended up bringing up more questions than it has answered.

Famously misunderstood wonder of the ancient world

Overlooked by many, the two famous Scottish warriors guard the main gate of Edinburgh Castle.

The most iconic structure in Scotland has been home to bishops, colonels, and Sean Connery characters.

One of the few surviving "Wigwam"-themed motels.

This erect, phallic geological spire wasn't always named so domestically.