A cache designed to be easy because of the high muggle density. The hint is designed to allow a very quick find when muggles are around, so don't look at the hint if you don't want it easy.
The Octagon House was built in 1799, and its address is 1799 New York Ave NW. It's open for tours and was the home of a President (James Madison) for six months after the British retaliatory burning of what is now known as the White House. Count the sides - strangely, not eight. Nearby is the American Institute of Architects.
At the geozone, you will find an object that is a common cache host, but strangely, rare in DC.