An overlooked oasis of quiet on the grounds of Washington's monumental basilica.

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

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

After hundreds of years of settlement, this once-bustling fishing village sunk into the Chesapeake Bay.

The remains of a failed attempt at medieval nerdery are hidden deep in the woods of Virginia.

Captain John Smith thought these cliffs were amazing in 1608 but sharks thought so 20 million years before him.

Exact replica of the ancient monument, but much, much lighter.

The beloved statue at the National Academy of Sciences is oh so inviting to sit on.

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

This unique historical monument features large concrete spheres designed to resemble fallen stars.

Remains of a historic fountain that was mysteriously lost in the demolition of a D.C. traffic circle.

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

The remnants of a wooden-hulled fleet built and abandoned in WWI, now home to a thriving ecosystem.

A cavernous three-story, 43,800-square-foot basement that was forgotten about for 60 years.

A historic neighborhood church is reborn as a psychedelic arts collective.

This lovely pocket park is one of the most under appreciated in D.C.

The oldest continuously operating fish market in the United States.

The longest escalator in the Western Hemisphere takes over three minutes to ride down.

Brain collection and database that narrows the gap between man and animal.

An astounding collection of medical specimens, including bits of President Lincoln.

An intricately designed junk art house with four extravagant junk art cars hidden in the suburbs.

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

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

There’s a special club house at the top for the bell ringers.