Members of Congress have traveled between the buildings on Capitol Hill for a century hidden from tourists, press, and storm clouds.

The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

Rumor has it the uncarved lump behind the three famous suffragists is reserved for the first woman president.

Corn-inthian columns with a uniquely American take on neoclassical architecture.

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

One critic described it as "middle Mussolini, early Ramses, and late Neiman-Marcus." Another called it an architectural "natural disaster."

An obscure public service from the U.S. government that redeems burnt, moldy, and soiled old greenbacks.

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

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

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

The sci-fi villain is a little-known inhabitant of the U.S. capital's largest cathedral.

World's first "penitentiary," meant to be humane, drove men insane.

This elaborate towering structure was once famed for its revolutionary height.

America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.

Step inside Lucy, the world's largest "elephant."

What remains of the simple red brick chapel where the women's rights movement began.

The home, museum, and death site of Kodak's influential founder.

The birthplace of America's favorite fruit-flavored mystery dessert.

One of the Seven Wonders of the Modern World holds the world's tallest metal staircase.

A 98-room castle in the middle of Toronto that bankrupted a 19th century electricity multimillionaire.

The site of William McKinley's tragic assassination is only marked by an underwhelming boulder.

Genesis of modern hydroelectric power.

A beautifully designed asylum was resurrected as a hotel and art center with a ghost story or two.

The seat of Buffalo government is a gorgeous Art Deco palace.