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

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.

Corn-inthian columns with a uniquely American take on neoclassical architecture.

One critic described it as "middle Mussolini, early Ramses, and late Neiman-Marcus." Another called it an architectural "natural disaster."

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

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

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

This stunning blue and gold room changed cities twice before becoming part of the Smithsonian.

This lovely pocket park is one of the most under appreciated in D.C.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

A unique set of caves that spits waves back out into the ocean.

An authentic replica of an Asian temple and garden hidden amongst the natural beauty of Hawai'i.

Dr Barnes' $25 billion private collection of art and arboretum.

Golden and naked, the figure that was once the highest point in New York is all that remains of the second Madison Square Garden.

Yo, Adrian!

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

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

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

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

This seemingly out-of-place gas station by the Watergate hotel was once described as the most expensive gas station in the world.

The only tennis court that falls under the jurisdiction of the central bank.

This church built atop a gas station promises to "equip you for the next stage in your life’s journey."

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

The national park was once a plantation estate.