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

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

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.

The only road through the heart of Glacier National Park.

This spectacular track has run continuously since 1882.

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

Considered by many to be one of the most dangerous highways in Alaska.

A monument commemorating the role of Alaska's native Tlingit guides in the Klondike Gold Rush.

The northernmost international land border crossing in the United States.

The facade of this relic from the Klondike gold rush is decorated with over 8,800 pieces of driftwood.

A giant poultry statue immortalizes one of Alaska's more humorous town names.

The easternmost town in Alaska can only be accessed from Canada.

A classic gold rush hotel can be expected to pick up some ghosts along the way, and the Golden North is no exception.

The king of U.S. high points towers over every other peak on the continent.

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

A Norwegian-born sculptor created these soaring guardian angels at the entrance to Hoover Dam.

Experience a charming 1930's version of "infotainment."

This Native American settlement dates back to the Pueblo II period.

The remnants of a creative early method of wildfire prevention.

Visitors to this public park will also find the ruins of an old western fort.

Officially named the "Loneliest Road in America," this barren stretch of Nevada road offers almost nothing but sky and open fields.

When it was built in 1929, this historic bridge was the only place to cross the Colorado River for 600 miles.

A monument to the one-armed geologist who led the first documented expeditions through the Grand Canyon.