After decades of neglect, a historic house that once belonged to Mark Twain's relative burned early this morning.The James Clemens House built in 1858 was reduced to a crumbling shell after flames torched what was left of its roof. Wide swaths of brick walls collapsed at the rear of the old mansion, which was located at 1849 Cass Avenue.
The house, partially hidden from view by a brick wall and overgrown trees, was owned by controversial northside developer Paul McKee.…