"Dark Sky Park" is heaven on Earth for astronomers, one of the rare U.S. locations with no artificial light pollution.

A local prank turned town icon.

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

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

A gorgeous mural outside a beloved D.C. restaurant pays homage to famous Black Americans.

At Washington's Dulles Airport is a satellite museum (no pun intended) with three quarters of a million square feet of aircraft history.

The first memorial dedicated solely to the Black troops who fought for the Union.

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

A tribute to the beloved, kind-hearted "homeless mayor" of Silver Spring.

A girls' boarding school inspired by the Chicago World's Fair, once abandoned, now restored to strange and scenic glory.

Enormous piles of historically significant stones, dumped by Congress in a forest, and abandoned for 60 years.

A Civil War fort in the middle of Washington, D.C. has been swallowed by a forest.

Built by the patriotic residents of Boonsboro in a single day.

One of the only memorials dedicated to journalists who died in combat.

Once home to seven different roller coasters, Glen Echo has undergone many transformations since its founding in 1891.

Once the "Eighth Wonder of the World," this iron railroad bridge was decimated by a tornado.

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

A three-story tower of books about Abraham Lincoln is one of the more unusual monuments to the president.

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

One of the most influential presidents in U.S. history wanted only this plain, elegant monument as his lasting memorial.

A historic arena where the Beatles played their first concert in the U.S.

The unique traffic pattern named for an influential urban planner is also known as the Pedestrian Scramble.

Perhaps the most scandalous statue of America's first president.

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