Found at the Superman Homepage.
I had not known that the Kent Farm was an actual house or barn. Its in pretty wretched condition, but it also doesn't look like anyone has really been in there since the filming 35 years ago.
It kind of makes me wonder why Bryan Singer chose to remake the farm in the middle of Australia for Superman Returns, but his needs were fairly different, I guess.
I confess, I got a little sad seeing the Kent homestead in disrepair.