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

Rippling sand dunes frozen in the Arizona rock.

Dramatic river bend surrounds a natural red-rocked pedestal.

This whimsical Oz-themed park had a wonderful impact on the surrounding neighborhood.

The world's second largest single-dish radio telescope, once used to contact E.T.

This limestone cave offers an incredible view of the Río Grande de Arecibo valley.

The world's brightest bioluminescent bay.

A modern zoetrope on the New York City subway.

Three columns of volcanic rock shoot out of the ocean.

A peculiar mansion built by the troubled heir to the Winchester Rifle Company fortune.

A museum dedicated to the alleged Roswell Incident.

An emerald-green grotto just a short trip from Austin.

The oldest surviving bridge in New York City, which reopened to pedestrians in 2015.

Dr Barnes' $25 billion private collection of art and arboretum.

America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.

An experimental, automotive replica of Stonehenge.

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

An alley covered with 20 years of bubble gum.

America's most famous piece of self-built architecture.

Marta Becket's hand-painted theater in the desert.

Cryptic messages embedded in the New York City sidewalk.

The home of aviation trailblazers, in a remote corner of the big city.

First a horse rendering plant, then a 19th century landfill, this beach is full of glass from thousands upon thousands of broken bottles.

The famous author's cottage hideaway.