Copenhagen's celebrated theme park and gardens.

What was once believed to be a church floor turned out to be the artwork of geology.

These dramatic cola-colored falls have appeared in a poem by Henry Wadsworth Longfellow and a song by Sufjan Stevens.

A mechanical clock built in 1914, with a rotation of 12 historical figures on its face.

This steep-walled ravine contains animal-shaped formations made from sandstone.

The former home of the 11th president of the United States.

The National Park Service’s best-kept secret with views that rival any in D.C.

A 30-mile-long glacially-carved canyon leads to a massive pair of glaciers.

Beneath the southern end of the Golden Gate Bridge is the “Gibraltar of the West Coast,” a fort built to protect the San Francisco Bay from naval attack.

The walls of the statehouse tell the story of Ohio’s prehistoric past.

A small town museum celebrates the history of the Ohio county that produced Annie Oakley and other famous figures.

You can walk through the first Boeing Air Force One, which famously carried JFK's casket from Dallas back to D.C.

This unassuming home was once “grand central station” for the Underground Railroad.

Once designed as the entrance to Buckingham Palace, this structure was later relocated and stands as a victory arch.

The location where the American Revolution ended.

An art deco ice cream shop covered in vintage train station tiles.

These cabins mark the site where our 11th president was born (probably).

The former home of the man whose radical ideas changed the nation.

The Kirkland Monument remembers a selfless Civil War hero who braved the battlefield to give water to his dying enemies.

Developed by focused shutterbugs, this museum exposes visitors to more than 6,000 different cameras.

A secretive collection featuring objects that were designed specifically for U.S. intelligence operations.

The last holdout of a pre-Civil War rebel who took the matter of slavery into his own hands.

Coins and medals straight from the mint await visitors to this shop in the nation's capital.

Along the edge of this fountain are 365 smaller fountains that represent the days of the year.