I don't know that you find much information... I am aware of an old house (if it is still there) southwest of Palmyra (Marion County) that is supposed to have slave chains in the ~basement~. I know nothing of Hannibal. There are two old homes in Monroe County, one in and one just outside of Monroe City, that are supposed to have slave chains in the lower extremities of the homes. There is a home just east of Moberly that is supposed to have slave chains like wise... ~don