Chris N.
Yelp
This impressive building is a beautiful remnant of the golden age of the United States. At the time of the completion of this mansion, the United States was an emerging world power, enjoying huge advances in technology and greater general prosperity for its' citizens. Larz Anderson was a proud member of the Society of the Cincinnati. His wife, Isabel, did a tremendous thing when she donated the building to the Society in later years. Because of her generosity, everyone can now enjoy this architectural treasure, situated among the many mansions and embassies on Massachusetts Avenue.
The Society of the Cincinnati, named after Lucius Quinctius Cincinnatus; a Roman General who was nominated dictator of Rome, but chose to give up the reins of power to return to his farm, is a hereditary and patriotic society for male descendants of Revolutionary War Officers of France and the original 13 colonies of the United States (both Army and Navy). It is appropriately named, as Washington did the same thing at the conclusion of the Revolutionary War. Established in 1783, as the American War for Independence drew to a close, the Society of the Cincinnati is the oldest private patriotic organization in the United States. The organization focuses a vast deal of its' resources on education outreach and grant activity. You can find out more about the membership criteria here: http://www.hereditary.us/cin_membership.htm
Not forgetting the ladies, there is a huge and impressive building in Washington which acts as the headquarters for the female descendants of Revolutionary War soldiers, sailors and patriots (with documented service as officers, enlisted - both militia and continental forces - and certain civilians). The DAR headquarters is located across from the White House Ellipse. The male equivalent of this organization is the SAR, and their headquarters is located in Louisville, KY.
As noted, the tours are free-of-charge to the general public. You don't want to miss seeing the beautiful furniture, tapestries and overall architecture of Anderson House if you have time while you're in DC. I found this link, which gives a nice overview of Anderson House and hope it remains active for a while: http://www.youtube.com/watch?v=cevbsvJCLoc