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

The school tested mustard gas for the U.S. Army during World War I.

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

A museum cafe showcases Native American dishes and indigenous ingredients from across the Western Hemisphere.

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

A fantastic array of trays and cables once whisked books over to the Capitol at 600 feet per minute.

Rumor has it the uncarved lump behind the three famous suffragists is reserved for the first woman president.

An atomic bomb-proof strongbox protects the U.S. Constitution from terrorists and thieves.

The oldest continuously operating fish market in the United States.

Government testing at the asylum briefly explored using marijuana as a "truth serum" on Nazi prisoners of war.

The national park was once a plantation estate.

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

A nostalgic bibliographic gem.

The beloved statue at the National Academy of Sciences is oh so inviting to sit on.

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

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

These unusual rooms on wheels are holdovers from the 1960s.

The system of air guns are fired off remotely to scare any trespassing avians.

The romance of early commercial flight still fills this Art Deco destination.

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

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

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

An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.

A building so large that it has its own weather.