These petroglyphs created by ancient Arizonians have withstood centuries of exposure to the elements.

Legend says train robbers stashed their gold within the depths of this unusual cave.

Stairs often replace streets on the steep slopes of this old mining town.

The world's largest rose bush has literally outgrown the pioneer museum it was planted behind.

This Old West hotel, the longest in continuous operation in the state of Arizona, is claimed to be haunted.

A phenomenal assembly of pueblos in New Mexico is the most complete example of ancient ruins north of the border.

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

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

More than a century old, this trading post resides in the Navajo Nation.

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

Look closely and you’ll notice that the color changes a third of the way up the tower.

This replica of the Greek structure is in the heart of Nashville.

Bronze statue marks the spinach capital of the world.

This Tennessee museum is dedicated to a tragic railroad hero who inspired the famous ballad that bears his name.

The old Route 66 town straddling Texas and New Mexico died along with the Main Street of America.

This refurbished gas station is one of the oldest in Texas, located on the original Route 66.

This water tower slanted at an uncomfortable angle off the old Route 66 was an ingenious marketing ploy.

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

Vulture Mine was Arizona’s most productive gold mine, and instrumental to the development of Phoenix.

A lingering bit of Space Race nostalgia lies in the middle of the desert.

Red sandstone structures dominate this landscape, which has been inhabited for some 5,000 years.

Ancient human, animal, and geometric figures drawn in the earth.

These markers are used to document elevation changes around the famed dam.

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