In August 2017, a historical plaque was placed near this cache to commemorate the first atomic clock, which was developed here when it was the site of the Natural Bureau of Standards. Later, the international satellite operator, Intelsat, was located nearby.
Super-accurate time keeping has many scientific and industrial uses. One of those uses is measuring the tiny differences in the time it takes for signals from different satellites to arrive at a given location - the foundation of the Global Positioning System and hence geocaching.
Park and dash parking is (sometimes) available nearby on Connecticut Avenue NW. Otherwise, try Upton St NW a little further away, or further still on Tilden St NW.
It can be busy here with muggles - as needed, use the three hints of increasing specificity to help with a stealthy find.