This beautifully designed star-shaped fort was the premier defense system of the late 1500s.

Of the many chalices in the running for the Holy Grail, this one in Valencia Cathedral sure looks the part.

One of the world's tallest waterfalls wasn't revealed to the world at large until 2006.

Burping, gurgling geothermal mud pots by the Salton Sea.

The splendor of this 17th century golden chapel has led it to be called the "eighth wonder of the world."

This Old Testament garden features 100 plants from biblical times.

This beautiful ancient site is dotted with perforated sandstone pillars considered sacred by some Native American groups.

This stretch of beach along California's central coast is a busy highway for the largest seal in the northern hemisphere.

A historic London pub with prison cells in the cellar and a "spy room" on the second floor.

Mine your own precious stones.

For thousands of years, Native American hunters drove buffalo straight off this cliff in Montana's Yellowstone Country.

After covering almost 1.5 billion acres, the survey's still not finished.

In addition to fine dairy products, the world's most beautiful milk shop also offers a feast for the eyes.

A small Richmond island dotted with the remnants of hundreds of years of history.

This central Nevada cave is the spiritual home of ancient and enigmatic pictographs.

Bubbling up from deep underground is the warm crystal clear water that fills the Warm Springs Pools, America's oldest spa.

The world's largest and most outstanding marl lake regularly changes color.

With over 340,000 artifacts and counting, there is something for everyone, often called the "Smithsonian of the West."

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

A gorge full of caverns where early humans lived alongside cave hyenas, giant mammoths and wooly rhinoceroses.

A preserved factory in the "Home of the Carrousel" is now a museum dedicated to the classic wooden ride.

This tiny island featuring 9th-century Viking ruins is only accessible at low tide.

One of the last surviving C-97s sits in a field in front of a Wisconsin inn.

Lyon, France is home to two remarkably preserved Roman theaters, one dating back to 15 BCE.