The largest hot spring in the United States is, as the name suggests, a stunning show of natural color.

The first declared National Monument in the United States.

At 135 years old and counting, this historic print shop is heaven for poster nerds and music buffs.

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

A relic of FDR's brief foray into utopian urban planning.

The tallest The Church of Jesus Christ of Latter-day Saints temple in the world soars above the Beltway.

Once home to seven different roller coasters, Glen Echo has undergone many transformations since its founding in 1891.

These unusual rooms on wheels are holdovers from the 1960s.

One street divides a single town that stands in two U.S. states.

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

This raised bulls-eye visible from space was the subject of an intense geologic controversy.

A ghost town that held steady longer than most, but finally gave up the ghost.

This quiet park's strange sedimentary spires were named after Kodak's color film.

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

Come for the speed, leave in love with the desert.

Once a menacing challenge for trailblazers, this trail is now the most scenic drive in Utah.

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

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."

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.

Paleoamericans built these ancient walls high in the Colorado Rockies as part of an extensive hunting system.

"All Mountains - All The Time."

An enthusiastically interactive mining museum that won't let black lung ruin the fun.

This underfoot portrait is the work of a disgruntled painter inspired by a tragic poem.