Limestone caves with spectacular showcase chambers.

This southwestern historic site was designed and built by an artist who wanted his work to "feel at home."

This 19th-century ghost town offers a stunning view of Lake Michigan and a journey through the region's industrial past.

As its grandiose name implies, this wooden dome is unsurpassed in size.

The former home is said to be haunted by the ghosts of the beloved mayor and his wife who lived here.

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

The Jewish section of the famous Boothill Graveyard was abandoned for nearly 100 years.

Opinions differ as to whether this Arizona tree was actually used as a Wild West jail, but that hasn't stopped the town from capitalizing on it.

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

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

One of the oldest Mexican restaurants in the United States air-dries its trademark beef in a dangling outdoor cage.

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

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

Once the product of an inexplicable gold strike, this ghost town is now home to one man and his love of classic machines.

A natural history wunderkammer in the middle of the desert.

Walk through the actual strap iron cells and solitary chambers of Arizona Territory’s first prison.

In this small Phoenix taxidermy emporium, you can find everything from a squid in a jar to a freeze-dried toad.

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

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

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

A reproduction of earth's many biomes.

Ninety feet off the valley floor is an ancient dwelling put under protection of the U.S. government by Teddy Roosevelt.

One critic described it as "middle Mussolini, early Ramses, and late Neiman-Marcus." Another called it an architectural "natural disaster."

A little marble compass above George Washington's (empty) tomb in the Capitol marks where D.C.'s four quadrants intersect.