A celebrity from the late Cretaceous period.

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

Largest Roman Catholic church in North America.

This historic building is now home to the Public Access Corporation for the District of Columbia.

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

Railroad officials in the early 1900s sought to spare travelers the sight of Roman soldiers’ private parts.

This groundbreaking 16th-century map is known as "America's birth certificate."

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.

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

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

A muscular Art Deco monument represents the struggle between regulators and unbridled markets.

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

Go take a picture with the inventor of the daguerreotype photographic process.

A monument in Washington D.C. marks the spot from which all other roads were supposed to stem.

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

There’s a hidden military meme engraved on the World War II Memorial.

Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.

Decades before the scandal, this staircase on the river was a literal "water gate."

The national park was once a plantation estate.

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

A church that bred legends, and served as an inspiration for the Da Vinci Code.

A little sculpture with a large wardrobe.

Cozy basement bar sports an inventory of over 2,000 beers.

Amsterdam's former hotspot for public executions and dissections.