Fairfax County General :
Welcome to Fairfax Underground, a project site designed to improve communication among residents of Fairfax County, VA. Feel free to post anything Northern Virginia residents would find interesting.
Ah - CIA - okay, then it's probably related to the Big Blue Spy Buildings south of 50 and north of Westfield (and west of 28) - National Reconnaissance Office. That paladium page calls it "DD". From ground level it always looked like a government building because of the flags outside, IMHO - wonder what the massive power is for, though?