This mighty white oak in Bethesda survived both the American Revolution and the construction of Washington D.C.'s metro red line.

A striking memorial to the 21 lives lost in an explosion at the Washington Arsenal

The privately owned cemetery that holds room for Washington's finest when they step down from life.

Franciscan monks created a facsimile of the Holy Land for North Americans who couldn’t afford the trip overseas.

Largest Roman Catholic church in North America.

Live data is transmitted from the Atlantic coast to instantly recreate the ocean waves in this fountain at the NOAA headquarters.

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

A suburban museum tells the story of a historic transportation network and even provides rides in antique trolley cars.

Dogs, cats, horses, monkeys, frogs, and fish are laid to rest at the second-oldest pet cemetery in the U.S.

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

The most accurate timepiece in the world.

When it comes to handsignals (and colonialism) rock always beats scissors.

Surrounded by a verdant garden and a backdrop of ivy, a monument to beloved poet Khalil Gibran stands outside of the Lebanese embassy.

In 1932, Americans honored their first president's 200th birthday by planting trees.

This brick-lined pedestrian walkway was once a railway tunnel used during the Civil War.

A former major munitions plant that has been converted into a sprawling art space.

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

This lovely picnic spot featuring thunderous jet landings is an aircraft spotter’s dream.

At 207 feet, one of the world's longest continuous escalators.

This unique historical monument features large concrete spheres designed to resemble fallen stars.

The national park was once a plantation estate.

The only National Monument ever to go missing for nearly 50 years then resurface in a dump.

The oldest continuously operating fish market in the United States.

This lonely waterfront memorial to the men of the Titanic was erected by the "Women of America."