The insides were stripped bare by the flow of time and enterprising scavengers. At least the stone floor (mostly cracked) is still here - but there doesn't seem to be any walls or floors inside the building, it's a one huge hall. Perhaps it was used as a warehouse?
In other words, plenty of open space to do anything you want. None of your friends moved in to this one, apparently preferring the smaller structure - the one which is more than just a pile of stones that is.