The largest natural travertine bridge in the world is nestled in a small canyon in central Arizona.

A reproduction of earth's many biomes.

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

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

An ambitious developer built what was once the world's tallest fountain in a Phoenix suburb.

Originally conceived as part of a proposed Arizona State Capitol building in the 1950s, this structure built in 2004 stands as a monument to the architect's legacy.

The massive, incredibly rare instrument is over 11 feet tall with a range so deep it goes lower than humans can hear.

This Arizona observatory is famous for investigations into Martian life, and as the place humans first spotted Pluto.

A planet-hunting astrograph built in the 1920s to seek out the so-called "Planet X" beyond Uranus.

The final resting place of the businessman-turned-astronomer who helped discover Pluto stands near his observatory.

Crafted in 1911, this steam locomotive spent its entire working life in Flagstaff.

A replica of the flagpole that gave a frontier town its name.

Ancient pueblos built into the base of a natural canyon wall.

The first of the iconic American roadside attractions lives on as a college mascot.

This 1930s log cabin began as a taxidermy museum but is now a popular country music venue.

A nature and cultural preserve named for its multitude of petroglyphs carved by the Northern Sinagua people.

An incredible airplane graveyard sits outside this small museum dedicated to preserving aviation history.

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

This Moab institution functions as both a rock store and a small natural history museum.

This site is home to ancient petroglyphs and pictographs dating back to 6,000 B.C.

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

This unique art installation used boiler tubes from a decommissioned power plant to resemble Antelope Canyon.

These mid-century motels once housed the workers who built the Glen Canyon Dam.

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."