A derelict bit of transportation infrastructure hidden in the woods.

A traveling postal dog covered 48 states and more than 140,000 miles, and he lives on as taxidermy, patched up with a rabbit's foot and a pig's ear.

The only Civil War battle in Washington D.C. took place near this highest natural point in the city.

A lovely aquatic park built by a one-armed Civil War veteran who made a fortune from lotuses.

Four bald cypress trees in Lafayette Square, across from the White House, mark the southern edge of a 100,000 year old cypress swamp.

This leafy estate is worth $18 million and is so grand it has two mailing addresses.

Light bulbs, scrap wood, and tinfoil comprise this homemade throne of the gods.

This lonely waterfront memorial to the men of the Titanic was erected by the "Women of America."

This imposing Masonic temple a mile from the White House was the first public library in Washington, D.C.

The first purpose-built art gallery in the United States is once again open as a center of craft arts.

The most decorated dog of World War I is preserved in the Smithsonian.

A Civil War fort in the middle of Washington, D.C. has been swallowed by a forest.

A monument in Washington D.C. marks the spot from which all other roads were supposed to stem.

There's a 12-foot-tall replica of the Washington Monument hidden under a manhole nearby.

A tiny piece of the Moon is embedded in this stained glass masterpiece.

This grand gothic brewery has been pumping out suds for over a hundred years.

The site of the climactic scene from the classic horror film is now a historic landmark.

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

The United States Capitol's former columns still stand.

The cave where two British judges hid in exile after sentencing the king to death.

A water pumping station disguised as a residential home to assuage concerned neighbors now tricks most passersby.

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

A nostalgic bibliographic gem.

During the Industrial Revolution this “Temple of Invention” was full of intricate miniature machines and gadgets.