The original vault that held the president's remains still stands, empty, not far from where he was finally buried.

A military museum and library dedicated to the citizen soldier.

When you visit his grave, be sure to rub the Great Emancipator's nose for good luck.

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

Eight feet in diameter and more than 24 feet around.

A pop-culture attraction outside of Dyersville, Iowa, hits a home run.

This 1960s kinetic artwork has been restored and is once again whirling away in downtown Minneapolis.

The first declared National Monument in the United States.

A true roadside icon standing on the same plains that the herds once roamed.

The world's largest mountain carving could fit all of Mount Rushmore inside it many times over.

Three and a half miles of cliffs, rocky beaches, Gilded Age mansions and 40 Steps to nowhere in particular.

The small first-floor apartment where the author wrote her Pulitzer Prize-winning book 'Gone with the Wind.'

This distinctive Crescent City tradition dates back to the days of horse-drawn carriages.

The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

Corn-inthian columns with a uniquely American take on neoclassical architecture.

Perhaps the most scandalous statue of America's first president.

The actual model from the original "Star Trek" series is now on display at the National Air and Space Museum.

The oldest standing structure in downtown San Diego.

A sculpture of the famous photograph stands on San Diego's "Greatest Generation Walk."

Ruins battered by centuries of war and disaster offer a wondrous glimpse of medieval Ireland.

A particularly disconcerting tribute to Irish martyrs.

The somber sculptures commemorating Irish Famine on the river Liffey in Dublin.

One of Ireland's most infamous prisons for rebels including men, women and children.

The last Victorian market in Belfast.