The second-largest ceremonial mound in the United States is an artificial hill that is loosely shaped like a pentagon.

An eerie and beautiful group of columns mark the site of a grand mansion lost to time and fire.

A spectacular remnant of an Adler and Sullivan masterpiece that was destroyed in 1972.

On the outskirts of a reborn ghost town, a decaying post office remembers the bad old days.

This rugged area of red rocks and arches is often considered one of the most beautiful places on Earth.

A common entry point to the Griffith Observatory trail holds its own wonders.

This historic hotel on Bathhouse Row in Hot Springs National Park has a storied history of gangsters and baseball greats.

In its day this historic fort held 100 cannons pointed in almost every direction to protect New York.

An 18th-century Spanish watchtower made entirely of seashell and concrete.

This fort down the Potomac from Washington, D.C. was once the only defensive fort protecting the capital.

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

One of the only Florida forts to remain in the hands of the Union all through the Civil War still stands as a historic stronghold.

Once a lonely sentinel on the edge of the Great Plains, this rebuilt trading fort offers a glimpse of life on the Santa Fe Trail.

The remnants of the fortress that saved Georgia from the Spanish still stand guard on their swampy island.

Where manatees are the snowbird vacationers in these balmy Florida springs.

The haunting ruins of Jack London's dream house.

After starting as a whimsical tourist attraction that eventually found its way to ruin, these renovated canals offer a lush and exotic locale on the Pacific Coast.

Miniature art that tells an enormous story.

It took more than 20 years and a sharp eye for one man to assemble this quirky collection.

When you can afford only half a road, you build only half a road.

The modest childhood home where the baseball legend and Yankees star learned to hit from both sides of the plate.

The Bucyrus-Erie model 1850B electric shovel, or "Big Brutus," the largest existing electric shovel in the world.

A dramatic, 360-degree recreation of Pickett's Charge in the Civil War.

Small plaque marks the spot, but the true center is located about half a mile away on a private pig farm.