One such place was the Old Slave House in Equality, IL.
I visited it on a school field trip back in the 1970's.
From our remove slavery and indenture look pretty much the same, but they're not!
So, if they have a "slave house" anywhere in Illinois it has to be PRE-Indiana Territory. That would put it back before very many people lived there. It might also refer to an ever earlier civilization in that area, and not to the present American civilization.
For example, the biggest Indian tribe (in terms of territory) in Oklahoma. the Chickasaw (headquartered in Tishamingo) have a tradition that they came from the far West.
We don't know how far West it was, but they had horses, and times got hard, so that places this story sometime after 1515 or thereabouts when Indians began acquiring Spanish horses. I'll guess the band with this foundation story lived somewhere along the Rio Grande.
Anyway, times were tough so they headed East. They cut a lead horse loose and followed the horse. This was in conformance with the instructions from God given to the tribe's shaman to "cut the horse loose and go to where he stops".
So they did so and ended up over in Mississippi. Later on they moved to Oklahoma
About that time (1850s) a band of folks in the Apostolic Charismatic Church of the First Born in Indiana decided to go West to Oklahoma.
Times were hard so the minister/shaman mixed the appropriate herbs, got in the sweat lodge, and had a vision or two. He came out and told the members of the church to "cut the horse loose and follow him until he stopped".
Best I can tell that particular horse kept going until he got to what we now call Zion National Park in Utah.
I'm pretty sure these stories are not just coincidental since one of the COTFB settlements at Altus was coterminus with a Chickasaw settlement, and COTFB folks are scattered all over Oklahoma (as are Chickasaw).
It looks like the same story, except that the COTFB band that went to Zion also had a couple of little girls who grew up to be faith-healers (a story that coincides with an Iriquois story) and had the story of the "three brothers" (which coincides with the foundation story of the true religion of the Delaware and the Mohican).
This leads me to believe that COTFB affiliation by American Indians has resulted in the development of a COTFB story board, and not the other way around.
Which leads me to my point ~ the "slave house" story could relate to a place where slaves were kept by the French or Spanish, long before that part of the world had any English or American settlers, or possibly even to the times the Indians still had villages and towns in the area ~ which would be right up through the mid 1500s. That's when times got hard and the locals moved East (see Cherokee moving to the Carolinas).
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If so, this particular house would be one of the oldest European constructed buildings in the Americas, or a holdover from pre-Columbian times ~ a true architectural and archaeological wonder!