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

These mouldering mansion ruins remember a time when the Catskills were nothing but luxury.

Six peaceful acres in a residential neighborhood dedicated to art and peace.

Hundreds of glow-in-the-dark objects light up a museum in a historic zinc mine.

A winding, cliffside stretch of road overlooking the Delaware River.

One of the U.S. Forest Service's only mansions is outfitted with a dinner table for floating food.

This once luxurious Catskills resort is now a haunting ruin.

The site of one of history's most indelible and horrific tragedies.

This little-known rival to the Library of Congress houses one of the largest collections of pre-1876 American books, newspapers, and manuscripts.

A planned settlement in Pennsylvania once housed the aristocratic refugees of the French Revolution.

The library of every book lover's dreams.

In upstate New York, gorgeous waterfalls and a watermill are slowly being reclaimed by nature.

Contrary to what one might expect, ice forms inside this small cavern during the summer and melts during the winter.

"Dark Sky Park" is heaven on Earth for astronomers, one of the rare U.S. locations with no artificial light pollution.

Over 100 concrete munitions bunkers are all that remain of a Pennsylvanian village seized by the US government.

A modern ghost town whose inhabitants were driven away by the growth of nuclear power.