Fireplace vents out these holes - why no chimney?

[bungalowrescued]

We just moved into a 1921 jumbo bungalow in Chicago. It has this fireplace, with a flue, and on the opposite side of the wall, on the exterior side, it has these holes. There is no chimney. There is no sign that this ever had gas. It has an electrical outlet, though it seems to match other outlets in the house that were added later. In the basement, there is another fireplace. It also has a flue, and vents out to another set of holes in the exterior wall, right next to the main floor fireplace holes. The tile roof does not appear to have ever had a chimney going through it. I have reached out to every fireplace company in the Chicagoland area, and nobody has been able to figure this out. One guy said in his 40+ years of working with fireplaces, he's never seen anything like this, and can't figure out what is going on. We are at a loss. How do you think the fireplaces originally worked? If we wanted to get them to be wood-burning, how could we do that? We are very much looking to restore the home and retain as much of its original features as possible. Please help us understand what may have happened here.