This stately 19th century library pushed architectural boundaries at a time when the public library movement was just taking off.

This monument marks the beginning journey of a wounded soldier's leg that ended up almost two states away.

The oldest surviving presidential residence in the United States.

The slate extracted from these Pennsylvania quarries was once hailed as the finest in the world.

Hellam Township is reputed to feature seven remote gates, which when passed through in the right order, open an entrance to hell.

Sail through this subterranean show cave that is home to a legend that would go on to name nearly everything around it.

A small granite block at this monument's base is the only part of Lincoln's Tomb outside of Illinois.

Enormous lake at the bottom of a unique cave system.

A "house to which to flee" for settlers in colonial Pennsylvania.

The tallest waterfall in West Virginia.

This general store is more than a century old and home to various oddities and antiques.

The highest point in South Carolina was once owned by an energy company that neglected it but now the state is taking it back.

The highest point in Tennessee, Clingmans Dome bears witness to the ravages of one type of insect.

A fascinating community art piece created by students, teachers, and noted Philadelphia artist Isaiah Zagar.

An American industrialist hoped this nature preserve could help save the North American bison.

One of the few remaining covered bridges in Lancaster County.

This massive sycamore tree has been labeled as one of the largest in the state.

One of the oldest Catholic churches in the U.S., situated just east of Gettysburg.

An enormous warehouse filled with parade floats collected from over 50 years of patriotic celebrations.

Intricate, eye-catching, award-winning rubber sculptures liven up this Pennsylvania town.

At the end of a street is a statue with no indication as to why it was created.

These small house replicas have stood proudly since the 1950s, even as the property has changed hands.

This covered bridge was used by both Union and Confederate troops during the Battle of Gettysburg in 1863.

Dedicated to extinct passenger pigeons.