A scenic fort on the harbor protected Philadelphia from an attack that never came.

Delaware's first railroad lasted only five years and spanned only 16 miles, but its ticket office has survived for two centuries.

The first marker along the famous boundary.

A toxic ghost town sitting atop a massive coal fire.

Dyed by iron oxide over centuries, these sandstone rocks rise thousands of feet into the sky.

The highest point in Delaware is located under a trailer so this marker across the street will have to do.

The highest point in New Jersey is marked by a massive, if simply named, obelisk.

This original Mason-Dixon line cairn placed in the 1760s was put in the wrong location because of the gravitational pull of the Allegheny Mountains.

The house that Frank Lloyd Wright "(shook) out of his sleeve at will" at the age of 86.

Frank Lloyd Wright’s most iconic home dangles over a Pennsylvania waterfall.

A Norwegian-born sculptor created these soaring guardian angels at the entrance to Hoover Dam.

Experience a charming 1930s version of "infotainment."

Nevada's largest cactus collection stands outside a candy mogul's small factory.

The most elaborate of 12 medieval arched doorways to the old city of Burgos.

Board a mine car and descend the #190 slope 300 feet underground into the Clark Vein of coal.

Narrow gorges and deep pools created by long-ago glaciers.

An industrial waste tourist attraction.

This school was designed to support the rebuilding of African American schools around Delaware.

The meeting of the northwestern corner of Delaware, the northeastern corner of Maryland, and the southern edge of Pennsylvania.

The tombstone of the founder of the lost town of Ogletown is now stuck inside a traffic median.

This family of wooden moose statues have become local celebrities in their hometown.

The third tallest lighthouse in America once guided author Stephen Crane to safety.

The oddly shaped, steam-spewing building is now an art studio and gallery.

This advertisement for talcum powder was painted on the rock face and has since defied removal.