Home to items never before seen by the public.

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

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

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

They sort through millions of dollars worth of diplomatic gifts on behalf of the government.

The grand marble structure next to the White House is Andrew Carnegie's temple to Pan-American diplomacy.

D.C.'s first central library was born out of a chance encounter with the philanthropist whose name it bears.

This mysterious structure by the Washington Monument is a flood barrier designed to protect the White House against rising waters.

Look closely and you’ll notice that the color changes a third of the way up the tower.

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

The bank that helped fund the Mexican-American War and the purchase of Alaska met its downfall after helping Augusto Pinochet launder money.

A line of blue paint marks the route of the inaugural parade.

The tallest The Church of Jesus Christ of Latter-day Saints temple in the world soars above the Beltway.

Rediscovered after a century, the father of the American Navy was reinterred in something dredged up from Davy Jones' Locker.

This palatial botanical garden is home to one of the largest pipe organs ever installed in a private residence, and a piece of Wood's cycad.

A winding district gerrymandered into the shape of a mantis.

A museum dedicated to exhibiting remarkable outsider art.

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

The design of this historic domed church was influenced by Thomas Jefferson and intended as a statement of religious freedom.

Meet some of the most prominent figures in Black history through life-sized wax models.

A hidden alley in urban Baltimore is a haven for graffiti artists.

A pre-Industrial Age iron furnace and the site of a nearly-forgotten piece of Black history.

What looks like a simple quaint estate in rural Pennsylvania was in the 18th century home to a small monastic community.

A dramatic, 360-degree recreation of Pickett's Charge in the Civil War.