In the basement of the U.S. Capitol Building is a hidden storage room full of ornate floor tiles leftover from the 1850s.

The world's oldest soul food restaurant is also one of its best.

This robust fence in front of a historic Georgetown home is likely made from hundreds of recycled Revolutionary War firearms.

The oldest continuously operating fish market in the United States.

A hidden passageway now marks the site of an assassination attempt on Ronald Reagan that some say broke a 140-year-old curse.

Architecture lovers won’t stop touching the National Gallery's 19.5 degree marble prow.

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

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

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

The only Leonardo Da Vinci painting in the Western Hemisphere.

The monument's pointy aluminum tip has been melted down by repeated lightning strikes.

A tiny monument to the unsuccessful attempt by Thomas Jefferson to place the prime meridian in Washington.

The story behind this beloved toy—named for Theodore Roosevelt and owned by his grandson—is more complicated than you might guess.

Garments from across the globe call this hidden gem home.

This unassuming passageway played a key role in one of the most important events in U.S. history.

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

The winding route passes through an enclosed alleyway, two tunnels, and leads to the White House basement.

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

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

The final residence of an educator, civil rights leader, and presidential advisor was also the first headquarters of the National Council of Negro Women.

A menagerie of concrete animals brought together from across New York City's parks.

Happy harbor seals frolic and snooze on this warm, sandy stretch of coast.

This forgotten Frank Lloyd Wright house is an architectural marvel at the end of a sleepy residential street.

This nonsensical smiling boat shuttles passengers between two places they could've easily walked between.