Twain's house in Redding was designed by W.D. Howells's son, John
Howells, who was a professional architect of some note. The house did
indeed burn down. My understanding--based on a conversation several
years ago with Alan Gribben, which I may be remembering imperfectly--
is that the house was rebuilt according to the orginal plans, but at 3/4
scale. I believe that the house is still in private hands, and not open
to the public.
Bowling Green State University