What is the Thing?

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

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

Miniature art that tells an enormous story.

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

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

Despite a recent paint job, the factory still sits empty.

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.

This historic national park is covered in the stunning ruins of red rock pueblos.

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

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

A beloved horticultural oasis on the grounds of a wealthy family's former estate.

This elaborate towering structure was once famed for its revolutionary height.

One of the now-less-hidden floral gems of the "Emerald Necklace."

Two thousand artifacts from around the world collected by one woman who loved to travel.

The only museum with its curator—and her pets—buried inside.

Those who own or stay at this 500-year-old, allegedly cursed house often meet terrible fates.

Two stone columns flank the grand Venice square, but there were supposed to be three.

In the past, Renaissance sex workers were encouraged to entice customers on this bridge.

According to tradition this is the oldest church in Venice, but its actual age is a mystery.

This palatial spiral staircase was so unusual the name "snail" was given to the noble family who built it.

An iron dragon with a long neck covered in feathery scales perched above one of Venice's most popular squares.