It's safe—and permitted—to walk across these twin natural sandstone arches.

Step into the cool deep past and unknown future of who begat who.

Oddly shaped rock formation, misassociated with a nearby utopian community.

An Ancestral Puebloan ruin that appears to burst into flames in the sunlight.

A striking, menacing sandstone peak towering above a landscape that's equal parts Mordor and the Moon.

The fifth-longest natural arch in the world, and the longest outside China.

Giant pinnacles in the sun-scorched lands of Southern Utah have been nicknamed "white ghosts."

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

Bizarre lunar-like landscape with thousands of large stone "hoodoos."

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

One of the world's oldest and most massive living organisms is a grove of quaking aspens.

This 4,000-foot-diameter hole is touted as "the most well known, best preserved meteorite crater on Earth."

Ninety feet off the valley floor is an ancient dwelling put under protection of the U.S. government by Teddy Roosevelt.

Most-visited and most-photographed slot canyon in the American Southwest.

Hidden inside this Arizona fast food franchise is an in-depth exhibit on the famed WWII counterintelligence program.

Ancestral Puebloan ruins, natural arches, and box canyons abound in this seldom-visited corner of Monument Valley Navajo Tribal Park.

Only known mainland rookery of the threatened Stellar sea lion.

The location where the iconic movie character declared it was time to go home.

An 18th-century Spanish watchtower made entirely of seashell and concrete.

A secret, rocky playground hidden amongst the plain white beaches of the Florida coast.

Mariners once used this prehistoric landfill as a navigational landmark.

Flip your own pancakes in this old sugar mill within a Florida state park.

Part of a highway network meant to connect Miami to Montreal, this 10-mile stretch of road made from red bricks is still around 100 years later.