This bridge over D.C.'s Rock Creek Park is sometimes called the "Buffalo Bridge" because of its four buffalo sculptures, which were cast from a single piece of bronze.

One of the three perfect vellum copies of this historic book known to exist is on display in a specially-designed case.

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

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.

The National Park Service’s best-kept secret with views that rival any in D.C.

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

While most wind tunnels test scale models, the "Cave of Winds" was large enough for actual airplanes.

A bas relief commemorates the "Nuns of the Battlefield" who cared for soldiers on both sides of the conflict.

The little-known, 300-year history of the area includes former lives as a bustling tobacco port, parking lot, and industrial dump.

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

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

A traveling postal dog covered 48 states and more than 140,000 miles, and he lives on as taxidermy, patched up with a rabbit's foot and a pig's ear.

A little marble compass above George Washington's (empty) tomb in the Capitol marks where D.C.'s four quadrants intersect.

The "lovely red Vega" of the legendary record-settling pilot.

Washington's iconic carousel has a nice piece of Civil Rights history.

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

A celebrity from the late Cretaceous period.

Home to a vast and influential collection of Shakespeareana.

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

The Byzantine, pre-Columbian, and medieval art at this stately mansion are some of the most under-appreciated collections in D.C.

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

One of the dwarven trees dates back to 1625 and survived the Hiroshima bombing.

A museum marks and documents the site of the Titanic's launch.

A scattered trail of street art adds a pop of color to the city's stark structures.