Hanging the TV, wall material unclear

Looks like drywall glued in front of stone, quite common as a renovation. How old is the house? (By the way, you shouldn’t turn all your holes into craters, what’s going to hold there anymore? :) )

Looks like drywall glued onto stone, quite common in renovations. How old is the house? (By the way, you shouldn’t enlarge all your holes into craters, what’s going to hold then? :) )

The building is from the 60s, I believe, and the apartment was completely renovated recently. Yes, the holes start to get bigger because the material is so porous. But they are 7cm deep anyway, and hopefully the anchors will hold. Drywall in front of stone would make some sense. With that hole, I hit resistance exactly after 2cm. With the other holes, it was still easy to go through after 2cm. And what could the right hole be? I didn’t even get 2cm in there..

It's hard to tell, but it definitely looks like a screw to me. Does it sound hollow there? As mentioned, drywall is often glued onto old, crooked plaster walls to quickly even them out and possibly hide cables underneath at the same time. But generally, they are glued. On wooden or metal studs, the panels are screwed in, and the screw hole is then filled. That would match the depth. Maybe a new extension of the wall starts exactly there? Or a former door opening that was closed off with lightweight construction? If it really is a screw, then there's nothing right next to it. Carefully drill sideways next to your marked elongated hole to this depth. That way, you can at least rule out having hit the screw exactly by chance.

I will continue drilling tomorrow. I will also try to free the metal thing a bit, maybe you can tell if it is a screw. At the moment, it already looks somewhat like a screw head. But the screw would only make sense if, as you described, an earlier door had been closed with a wooden/metal frame, right? I'm not sure if I understood you correctly.

But the screw would only make sense if, as you described, an earlier door with a wood/metal frame had been sealed off, right? I'm not sure if I understood you correctly.

Well, at least that would be a possible explanation that comes to mind. The other hole and the fact that this is an older house that has just been renovated looks very much like drywall on a solid wall. That there should suddenly be an extra substructure right next to it is unusual; a sealed-off opening would be one of the few reasonably sensible ideas. You haven't said yet whether it sounds hollow there? Just carefully exposing next to it tomorrow will surely help. :)

No, the wall doesn’t sound hollow anywhere, not even directly at the hole with the potential screw. It sounds the same everywhere.