First off here's some pics of the cleared out second floor
here you can see that the joists don't reach all the way across! God only knows what the original builders were thinking jut sistering other beams on. It's barely holding up the third floor. Add that to the fact that it's leaning on a wall that's directly over the spot where they cut the joists on the ground floor and we have a serious problem. I spoke to my engineer and he suggested sistering them all the way across with engineered LVL beams. This place is going to be indestructible when we're done with it.
And now that the back wall is out of the ground floor you can actually see the whole space. This is from the back (NE) corner
Here's from the SW
And the NW
Here are some pictures of the floor. There was hardwood, covered by plywood, covered by linoleum, covered by parquet, covered by another layer of linoleum, covered by another layer of parquet!
I found myself extremely happy that I hired people to do this job.