Wow...3 images from me in one month??? Yeah, I know. :)
No, that is not the remnants of a green carpet. That is moss. That means that the wood floor is like a sponge. Step on it, and you would be three floors down before you even knew what happened.
Abandoned places are really fantastic for photographers. But they are inherently very dangerous. Having a guide, an official guide, is invaluable.
Christian VanAntwerpen has been my guide the last few times through the old Traverse City State Hospital, and I just can't say enough good things about him. Professional, accommodating, knowledgeable, and friendly. Abandoned buildings are rife with hazards, and they are constantly changing. Chris knows the issues each building presents at any given time, and makes sure that everyone remains safe while also making sure we get the shots we want.
I have been doing photography for 40 years, and Chris is one of the best guides I have ever met.
Addenda, 9/26/22:
I have been asked to provide more information on the location of this photo.
This is what was termed a "sun room", though the windows don't exactly lend themselves to the description. It was realistically what we would call a "social gathering area" for the patients on the 3rd floor of this building. It would have had chairs and perhaps a couple sofas, and small tables. The place I was standing in when I took this shot was a doorway of what was a nurses station overlooking the sunroom. Originally this was a tuberculosis ward, but eventually it evolved into the children's ward. In either case, this room is as close to "outside" most of the people who lived here ever got.
There are a lot of things that you have to pay attention to when you are going through these buildings, as this floor illustrates. If you put your foot in the wrong place, you could die. You want to get the good shots, and you are paying attention to all of the elements which go into that, but you also have to pay attention to your surroundings. That is one of the reasons for my glowing praise for Chris as a guide. He understands the complexities of these structures as they are used by photographers, and he is very careful to make sure that we remember to pay attention to safety first, and aesthetics second. At the same time though, the whole reason that this is such a poignant photographic subject in the first place is because of its history, and because of the very real people who lived...and died...in these rooms. You never want to lose sight of that either, because even though people have not lived here in almost half a century, those people are still ultimately the subject of every last one of the photographs taken here, by me or anyone else. I consider them to be portraits in that sense, even though they do not visually have anyone as a visible subject. The subject is always (for me at least) the people who lived here. The people, in this case, who sat in this now dangerously decayed gathering area enjoying each other's company and the scant but precious sunlight for a few hours before having to go back to the isolation and darkness of their rooms.