The Underground railroad was made up of houses and churches where slaves could find a place to hide and continue on their way to freedom. Here's a link to one such church in Detroit Michigan. Second Baptist Church
I've dealt with the subject of slavery in some of my historical books. When researching Lizzy's Hope, I read all I could find, at the time, from former slaves that was written during that time period. It was quite an eye opening experience. To understand how they thought of themselves and not what we've been taught today. It bode well to my characters and I received quite a few compliments from African Americans who read the book. If you're writing during this time period or about this subject, I'd encourage you to read as many books as possible by black authors during that time period.