This seemingly out-of-place gas station by the Watergate hotel was once described as the most expensive gas station in the world.

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

The preamble to the U.S. Constitution written entirely from vanity license plates hangs in the Smithsonian museum.

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

The most accurate timepiece in the world.

Largest Roman Catholic church in North America.

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

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

The actual model from the original "Star Trek" series is now on display at the National Air and Space Museum.

The walls of the iconic dome are hollow and have a secret stairway.

A museum cafe showcases Native American dishes and indigenous ingredients from across the Western Hemisphere.

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

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

Home to items never before seen by the public.

The site of the climactic scene from the classic horror film is now a historic landmark.

An abandoned textile mill that is now home to art and concerts.

Affectionately known as "Lord Bot," this historic statue has a cult social media following and rightly claims to be “the most metal inhabitant of the Wren Yard.”

The final resting place of a space program monolith.

The iconic boulevard is the perfect place to catch sight of a bicycling skeleton, a levitating Satan, or a chef with his head stuck in a pizza.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

Mai Tais and Navy Grog served up in one of the original tiki bars.

One of corporate America's best-kept secrets is also one of the most publicly displayed.

This isn't your average roadway—it's actually a National Park and a transportation pioneer.