Knocking out walls
Appleseed knocked out the parts of the rear wall that will form the garage doors. Apparently this is dangerous and can collapse the building so I went to Chicago that day. You can see from the picture below where they installed a steel beam to reinforce the wall, and covered up the openings with plywood. They're also digging for the concrete floor footings. The digging revealed the original base for the wooden support beams. I thought it was interesting these were brick, but now that I think about it, I don't what else they would have been.
Finally, they've started building the forms to pour the concrete ramp coming down from the alley.