This canyon is named for a unique geologic formation where the river vanishes underground near the mouth of the canyon and reappears farther down.

A miraculous natural phenomenon known as "the spring that breathes."

The tallest waterfall in West Virginia.

One day a year it is legal to jump off of this astoundingly tall bridge that spans an Appalachian gorge.

A museum dedicated to the history and exploration of both popular music and science fiction.

At the most northwestern point of the contiguous United States lies a trail leading through an ancient forest to stunning cliff-side vistas and massive oceanside caves.

Shoreline strewn with the remains of ghostly fallen trees.

A sacred site for Native Americans surveyed by George Washington and owned by both King George III and Thomas Jefferson.

The damming of the Colorado River buried an iconic geologic formation before record-breaking drought brought it back.

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

A sculpture for the sun and stars, created by Nancy Holt.

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

This rugged area of red rocks and arches is often considered one of the most beautiful places on Earth.

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.

The hike through a narrow river flanked by the 2,000-foot-tall walls of Zion Canyon is one of the best in the world.

An immense cave that has served as an outlaw's treasure trove, an underground dance hall, a nuclear fallout shelter, and much more.

The bridge continues the legacy of President Franklin D. Roosevelt's New Deal policy.

A serene temple with stunning stained glass hides in downtown Dallas.

This beautiful grotto is one of those places where you can't believe you're just outside Austin.

The Grand Canyon of Texas.

A sculpture made of 10 Cadillacs as a monument to the "Golden Age" of the American automobile.

An emerald-green grotto just a short trip from Austin.

In one of America’s oldest mountain ranges, a long-awaited section of a scenic highway is now open to the public.