Hidden in plain sight on a pair of Manhattan subway tunnels are a pair of public instruments that sing to each other.

Mysterious 500-year-old tapestries depict a unicorn hunt.

Whisper secrets in a busy station only to be heard on the other side of this acoustic arch.

Elevated freight railway turned wildly successful urban park.

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

One of the most influential presidents in U.S. history wanted only this plain, elegant monument as his lasting memorial.

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

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

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

The remains of Martha, the last known passenger pigeon, serve as a tool to educate about conservation.

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.

The most decorated dog of World War I is preserved in the Smithsonian.

The first purpose-built art gallery in the United States is once again open as a center of craft arts.

Home to items never before seen by the public.

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

A collection of the best toys ever made, The National Toy Hall of Fame is filled with kids, fun, and for some reason, a bird preserve.

The home, museum, and death site of Kodak's influential founder.

The Metropolitan Police refurbished the blue box (perhaps not coincidentally) the same year "Doctor Who" returned to TV screens.