A self-built castle made by a mysterious man.

This 4,000-foot-diameter hole is touted as "the most well known, best preserved meteorite crater on Earth."

A geological mystery on Camelback Mountain.

An urban laboratory.

Most-visited and most-photographed slot canyon in the American Southwest.

The story of Two Guns, Arizona could easily be described as a Shakespearian tragedy on Route 66.

A stealthy Apache hideaway that became the haunting site of a mass grave.

A motel dedicated to Southwestern nostalgia.

An artificial crater field that trained astronauts for lunar exploration.

One of the largest, oldest, darkest, quietest motel rooms in the world.

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

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

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

A world-class observatory in the California desert.

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

A Mars simulation in the southern Utah desert.

A shady solar power system that couldn't hold up to the harsh desert conditions.

Stepping away from the glitz of mobsters and casinos to learn about the other history of Vegas.

This pseudo-steampunk weapons facility is the world's largest wood and glue structure, and packs quite a wallop.

Suburban observatory was personal lab of the father of modern astrophysics.

Decommissioned experimental solar facilities that pioneered solar energy technology.

Metal water storage tank turned ethereal concert hall.

A house carved into a rock in the 1940s.

Self-sufficient greenhouse floating on the Hudson River.