Giant acorn-shaped 19th century gazebo from which suburban Washingtonians gazed upon the original "silver" spring.

A benevolent, 16-foot-tall river dragon lives on a suburban lawn.

Concerned residents saved this historic house and garden from demolition.

The rooster who crossed the road lives on forever in Takoma Park, Maryland.

This American Civil War-era fort still stands near the border between Washington, D.C. and Maryland.

A diminutive plaque recalls the treetop sniper who almost killed Abe Lincoln.

The oldest building in the District of Columbia was preserved because of a mistaken connection to George Washington.

In the middle of a busy airport, a statue honoring the astronaut who told Houston that Apollo 13 had a problem.

Around half a million years ago, these magnificent columnar basalt cliffs were formed from cooling lava.

An architect's childhood fantasy treehouse made real.

A beautiful geyser under environmental threat.

The only natural lake in the world that drains into both the Atlantic and Pacific Oceans.

The site of Paul Revere's historic two lantern warning.

Ruins from the Parthenon and petrified wood line the interior of one of the world's most famous monuments.

The whole world in one water tank.

Dedicated to extinct passenger pigeons.

Named after an outlaw who used the basin as a hideout.

This millstone-topped marker details the history of a mill that served as a landmark for both Union and Confederate soldiers during the American Civil War.

A glimpse of the Pacific Northwest‘s indigenous culture in Washington, D.C.

An echo chamber with a waterfall wrapped around its base at the Embassy of Canada in Washington, D.C.

A spectacular tribute to statesman and philanthropist Andrew Mellon.

The world's oldest continuously operating airport was founded by the Wright Brothers.

A relic of FDR's brief foray into utopian urban planning.

A lawn full of retired spacecraft on display at one of NASA's first research labs.