The Mysterious Dig, Part 1

Out for a quick walk in the woods, sleeves rolled up and bare-handed to try to get some sunshine although it's 41 degrees, I find, a little bit out of the way at the woods' edge where I haven't stepped before, a broken slab of concrete. Nobody would carry such a thing into the woods; there are no buildings in these woods. I brush the leaves from it and discover a second slab. Then a third. Then a fourth. Then a fifth. Digging and raking with my bare hands and a stick, I uncover more and more. A structure collapsed here. Then I found a rusty brace of some kind (outlined in blue), partway beneath a slab. Later I find a second one. It's a site. What is this place? What was this structure?

I found there also a steel tube, what I think was part of a gas line (outlined in green), sharply and deliberately bent at one end, exactly like the 50-year-old one at my house that was disconnected and deliberately bent so it could never be used again, when a new one was installed. I find a yellowish brick stamped "St. Louis" (outlined in yellow). Then I find what I think is a remnant of a vertical wall (outlined in pink); this material is different and more brittle, mixed with native stone. I keep raking right there, and just like a real archaeologist I find a shard of pottery; in this case, thick white institutional china, with dark-green stripes. Someone ate here. Was it a barbecue pit? It's too far from the dwellings, and too close to an old-growth tree, and if it had been a barbecue pit it wouldn't have gotten so large -- the site got larger as I uncovered more. I thought of going back for tools, but I'd dug enough for one day. Tomorrow I'll bring tools and a measuring tape and try to uncover the extent and solve the mystery.

There was also some synthetic material, very deteriorated and hardened (melted/burned?), and I'm showing a photo in case someone knows what it is--perhaps a form of insulation?

There was a boys' camp on this property, and I've heard tell of a chapel that existed pre-1957, when the dorms (now ruined, and a quarter mile away) were built. Could this be it? It does not appear in aerial views taken in 1954.

The Old Fresh Air Camp Ceiling

Now, before y'all start hunting around for this old camp seeking thrills and plunder, I want to let you  know 1)  there isn't anything worth anything, 2)  it's dusty, moldy, and has asbestos issues, and there's no water or electricity, and 3)  it's locked tight and it's on private property which I patrol with my pit bull Osama. This is the ceiling. Not healthy.