|photo courtesy of timmurtagh|
I have one bit of information on secret rooms around chimneys.
A lot of old farmhouses had those huge central chimneys, which could easily be 8x8 feet. But they became obsolete with the invention of modern wood stoves in the 19th c, or even gas or oil heat. So, two ideas: the framers had a certain way of framing houses, which allowed for these big chimneys, which they didn't vary when technology changed.Also, sometimes these old chimneys were torn down, and rebuilt as simple brick flues, without changing the walls around them much. We're working on a house in Maine where you can see the remnants of the big chimney, but there is a secret room around the "modern" 16x24 chimney.