After a short-lived attempt to bring America in line with the rest of the world, this road was left in metric.

Limestone caves with spectacular showcase chambers.

America's only nuclear missile silo open to the public.

This spectacular track has run continuously since 1882.

This church on a Tohono O'Odham reservation has stood since 1797.

Browse an impressive collection of passenger and military aircraft dating back to World War II.

This memorial pyramid marker honors one of the United States Government's first official camel riders.

The drama of nature in full effect in this Nevada State Park.

This immigrant bridge once spanned the Thames but is now a fixture of an Arizona city.

This cultural center showcases what may be the oldest ongoing community in all of North America.

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

This once-booming Gold Rush town is now home to a herd of feral donkeys.

A reproduction of earth's many biomes.

One of the world's largest telescopes, stares into the night sky with two huge mirrors.

A stone pillar marking the location of the westernmost battle of the American Civil War only honors one side of the conflict.

All of the 20 occupied houses in this mostly abandoned town feature some curious display of junk art.

At an isolated roadside rest area stands a monument marking where famous Western star Tom Mix died in 1940.

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

Some of the tallest ancient American ruins continue to inspire awe and curiosity.

The "Father of Arizona" tried to build a Zoroastrian fire temple on the hill where he's now buried.

This striking public art installation is suspended above a public park, designed to gently move in the breeze.

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

Come for the pizza, stay for a performance on the world's largest theater pipe organ.

The unusual burial monument of Arizona's first governor.