The once forbidden "secret cabinet" of erotic art from excavations of Pompeii and Herculaneum.

Crammed into a Baltimore row house is an oddities shop that sells everything from skulls to dead insects.

The trials and tribulations of marking Poe's grave.

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

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

This stunning blue and gold room changed cities twice before becoming part of the Smithsonian.

The oldest building in the District of Columbia was preserved because of a mistaken connection to George Washington.

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

A much-maligned monument to teetotalism.

Government testing at the asylum briefly explored using marijuana as a "truth serum" on Nazi prisoners of war.

A rotating cast of guys and dolls in front of a Washington, D.C. building.

People escaping slavery may have hidden inside a corpse vault.

The Byzantine, pre-Columbian, and medieval art at this stately mansion are some of the most under-appreciated collections in D.C.

A historic estate packed with George Washington's heirlooms, and its own nuclear bunker.

A Spiritualist house of worship where believers communicate with the dead in the spirit world.

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

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

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

Fittingly, America's museum of architecture is itself a magnificently designed old building.

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

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

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

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

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