One of many reminders of Tesla's scientific contributions overlooks the falls which inspired him.

A tunnel that brings more than a century of history to life from the deepest parts of the Niagara Gorge.

The largest ancient burial mound in Ohio.

The final resting place of the most famous sharpshooter.

The tomb was guarded by soldiers from both sides of the war, and some left their initials carved in the brick.

The graveyard holding the remains of George Washington's slaves was forgotten for nearly 200 years.

These sub-farmland caves are home to a majestic stalactite known as the "Crystal King."

A headstone tells the sad story of a lost little boy and his pet dog.

The childhood home of the Wright Brothers in Dayton.

In 1787, a group of delegates met at this very spot to drink, be merry, and ratify the Constitution of the United States.

The seventh largest spring in the world.

Life-size figures portray depot attendants, train crew, and passengers frozen in time at the oldest railroad station in Arkansas.

Often referred to as the largest spring in America.

Erosion and time have created a naturally-formed water park.

Giant granite rocks standing end-to-end like a train of circus elephants.

Once one of the world's great cities, Cahokia was a place of religious worship, trade and mass human sacrifice before being mysteriously abandoned.

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

Inside houses a vast collection of military aircraft and missiles spanning the ages.

The world's largest covered wagon is piloted by a giant Lincoln lawyer.