The château at Betz-le-Château in the South Touraine has a number of extensive man-made subterranean passageways. The word Betz is often associated with such workings that were used as wartime defences, escape routes and refuges.
The short publication Souterrains du Centre-Ouest (see left) has a number of diagrams showing thee subterranean workings. I have reproduced them below.
The excellent, full supporting article, written in French, along with other essays and images by Jerome and Laurent Triolet, are available here.