The life of one of FDR's possible mistresses is preserved in her palatial Hudson Valley mansion.

The only intersection in America where the buildings on all four corners were built pre-Revolutionary War.

Collapsing castle on the Hudson river was once the storage site of military surplus business.

One man's swirling six-acre monument of stone.

These 20-foot jaw bones honor a time when the leviathan bones were a sign that whalers survived the hunt.

A stunning, two-tiered waterfall made famous by poets, artists and the legend of a ghost dog.

This iconic 1,000-year-old medieval castle is a favorite of the film industry, most notably as the location for Hogwarts in Harry Potter.

What was once a trend-setting, phrase-coining icon of architectural splendor is now a rotting, forgotten hulk.

An abandoned cemetery lies in ruins as the surrounding forest swallows it whole.

Stonehenge has nothing on Castlerigg’s views.

This abandoned factory on the Hudson River once churned out a million bricks a week.

The Hudson River School comes alive at this palatial estate.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

A Victorian Gothic masterpiece housing a world-class collection of rare books and manuscripts.

This historic national park is covered in the stunning ruins of red rock pueblos.

The ruins of this gorgeous clifftop castle look like something from a fantasy novel.

A pagan tradition of draping trees with rags eerily lives on.

The remains of a grand castle that may have inspired Bram Stoker's Dracula.

Amazing and mysterious Neolithic settlement on Scotland's Orkney Islands.

The true age of this ancient stone circle is unknown, but its stunning vista isn't in question.

Possibly the oldest of Britain's ancient henges is also one of its most stark.

This Scottish burial tomb once held hundreds of ancient eagle bones.

Enter the world under the hill at this ancient UK burial chamber.

This tin chapel was built by POW's during World War II and is painted to look like something much more grand.