A church in St. Louis never just a building with a sanctuary in it. It was an entire complex, or even campus, in some instances.
The church would have a parsonage, or office for the priest or pastor.
And schools for Sunday and for the rest of the week, as well.
This little building, a later addition, is now a food pantry. Look at the density!
The houses where the congregants lived were just a short walk away.