I think there's a good chance it is. Not out in the sun, not in contact with ground/moisture, pretty consistent temperature. Wood can last a very long time under those conditions.

It could be. A lot of wood has been around for longer than that. Wood is easier to damage so I expect some has been replaced over the years, but there is no reason to think it wouldn't last in that application.

Yeah, I watch mine exploration videos and it's shocking how well wood in a dry and stable environment will last.

I wouldn't exactly call the environment on the green line as dry, especially in the summers.

The city of Venice is literally built upon timbers driven into the seafloor.

That haven't ever been replaced.

Maybe the chemicals they've used to treat the wood were so hardcore