At the moment, it is in the attic, except that the attic is unfinished, unheated, uncooled, uninsulated, and unelectrified - except for a long extension cord. Too hot in the summer, too cold in the winter. Plans are to finish the entire attic (eventually) and either keep the trains up there or else move the kids upstairs and trains to a room downstairs. For now, progress on the layout is slow as it is plain uncomfortable to spend any length of time up there.