An abandoned 1920s school with a mysterious history.

This abandoned school has had many lives since the early 1900s, and all of them doomed.

Hundreds of hopeful gold miners came here to get rich, but only two years later the small town was deserted.

A small Richmond island dotted with the remnants of hundreds of years of history.

Along the Palisades skyline are the ruins of a large mansion built in 1911 and demolished in the 1930s.

An eerie and beautiful group of columns mark the site of a grand mansion lost to time and fire.

A hidden gem on the lawn of the U.S. Capitol Building designed by landscape architect Frederick Law Olmsted.

Before Metro, Washington had a robust streetcar network—and you see the remains of this infrastructure if you know where to look.

Helen Keller once broke ground on this historic center for the study of technologies to benefit the hearing impaired.

A wondrous old library overlooking the nation's capital.

Once the supplier for noteworthy projects like the National Cathedral, this old brickworks now lies abandoned.

Bubbling up from deep underground is the warm crystal clear water that fills the Warm Springs Pools, America's oldest spa.

No one knows who painted this mysterious mural in a Penn State basement.

This fort down the Potomac from Washington, D.C. was once the only defensive fort protecting the capital.

The ruins of this long-abandoned unsuccessful gold mine can still be found.

This English-inspired Maryland garden is home to acres of opulent plant life including bushes shaped into an entire fox hunt.

The 320-year-old tree that greeted General Lafayette and rerouted an interstate highway.

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

With over 100 jam-packed rooms to explore plus elaborate tea services and events, the Mansion on O Street is a hidden treasure.

World's first "penitentiary," meant to be humane, drove men insane.

The highest point in Virginia can only be reached by passing through ponies and flowers.

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

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

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