A massive bur oak tree believed to be some 500 years old is the centerpiece of this quiet urban greenspace.

A replica of the self-taught naturalist's iconic cabin stands inside a library near his hometown.

At a mile long, the Fort Madison Bridge is the largest double-decker swing-span bridge in the world.

This small museum is dedicated to one of the most influential, yet obscure, jazz legends of Prohibition.

The lowest point in the state of Illinois, at the confluence of the Mississippi and Ohio rivers.

A natural sandstone bridge hidden in the Sewanee forest.

This grave marks the final resting place of a legendary frontiersman... unless it doesn't.

This simple gravestone remembers a pig who single-hoofedly raised $19,000,000 for the Navy.

A once-booming Mississippi River town with a history of racial violence is now eerie and mostly abandoned.

A turn-of-the-century architectural marvel built on healing mineral springs and salt licks.

This structure among the trees was the result of divine inspiration.

This former tuberculosis research hospital endeavored to cure the dreaded disease with fresh air and positive attitudes.

Visitors to this arboretum are greeted by three smiling giants crafted from sustainable materials.

In the Shawnee National Forest, amazing rock formations peer through the treeline.

Labor provided by Great Depression-era programs restored these 25,000 acres in Tennessee.

It's believed the famed author's parents once used this spring to gather water.

Patrick Dougherty's fantastic living tree sculptures, mind-blowing but temporary.

A collection of outdoor art by renowned muralist Robert Dafford depicts the history of a flooded city.

The farm where one of America's greatest leaders was raised is now a well-appointed landmark.

An enormous natural sandstone bridge in Kentucky.

The Trappist monk, prophet-poet, and rebel never really got to live out the eremitic life he was seeking.

Visit this playground of waterfalls, caves and sinkholes.

River pirates, murderous bandits, and serial killers used this Illinois cave as their debauched hideout.

These early tent-shaped grave coverings are unique to Appalachia.