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

An isolated island home to one of the oldest English-speaking communities in the region and Maryland's state dessert.

The United States' oldest Episcopal church still in active use.

A state park that once served as an important river crossing, and now offers protected lands for endangered plants and animals.

An original apothecary from 1792.

This abandoned Victorian-style house was built in 1884.

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

Located at the former Lorton Prison the Lucy Burns Museum tells the story of the 91 year history of the prison including the dark chapter of its involvement in the women's suffrage movement.

An out-of-place Air Force radar dome is all that denotes this park as a former missile launch site.

The semi-reclaimed ruins of this canal were once part of an ambitious plan to reroute the mighty potomac.

America's first federal monument.

The narrowest house in America is seven feet of pure spite.

This colonial tavern played host to George Washington, Thomas Jefferson, and other famous early Americans.

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.

The haunting "Hell House Altar" is one of the few remnants of an abandoned college that has been a magnet for local legends.

Once America's tallest structure, now a Baltimore landmark.

One of the oldest anatomical theaters in the U.S. still in use was once the site of an infamous cadaver riot.

Two dozen pinball games hidden away inside a most unlikely location.

This abandoned asylum was once a state of the art facility before devolving into one of the most deadly mental institutions in American history.

A remote horde of architectural treasures fit for Indiana Jones.

This dig site outside D.C. is known for its exceptionally high density of baby dinosaur fossils and dinosaur eggs.

A statue honoring 44 continuous years of greeting passing ships.

Oldest unrestored plantation house in America that is open to the public.

This Maryland farm is known for its amazing corn mazes and its 30-foot junkbots.