One of the most notable examples of secret government architecture that have already been revealed is the bunker at The Greenbrier, a luxury resort in West Virginia. Code-named ‘Project Greek Island’, the massive underground bunker beneath Greenbrier was built to serve as an emergency shelter for members of the United States Congress during the Cold War.
Capitol Hill (USA). 'You’re welcome to go inside the mighty, white-domed edifice and count the statues, ogle the frescoes and visit the chambers of the folks who run the country. Afterward, call on the neighbors. The Supreme Court and Library of Congress also reside up here, across the street from the Capitol.' http://www.lonelyplanet.com/usa/washington-dc