The cave is real
That "abandoned, decaying cobblestone path" is fake, but it is neglected. The stones are fake are there is clearly an artificial underlay, like the whole path was delivered in a roll and they laid it all the way down to the crick.
Just keep a light on and you'll be safe from the grue. IDK what you'd do against the lich tho. Good luck, I guess 🤷♂️