Just learned the following: PBS has commissioned at least a six-part series, based on an abolitionist and a "secesh" in Alexandria. They cross paths in Mansion Hospital--yes, a real place, often visited by Julia Wilbur, that had been Green's Hotel (the Confederate character in the series is Constance Green; the Union woman is Mary Phinney.) I am not sure about Constance as a real person, but Mary Phinney Olnhausen, the widow of a German emigre, worked at Mansion House and her recollections survive.
The hospital/hotel was torn down in the 1970s or so. It stood in front of the now-stately Carlyle House in Old Town, on Fairfax Street. An older friend once told me about going inside as it decayed--I believe it was, ironically, torn down as part of the restoration of Carlyle House, home to one of Alexandria's first families.
More to come, as I learn more.