Hi gump
The image is a bit soft, why I don't know but this is not the subject matter here.
As Norm says, you need a cherry picker to get the parallax on an even keel with the subject. If you do this sort of photography a lot (an awful lot) the cherry picker is out of the question but you can mount camera at the end of a mast and trigger it by remote. Special masts are commercially available.
There are three ways to deal with this:
1) Get a tilt and shift lens
2) Use the above mentioned
3) Correct falling lines with software. Photoshop it. (verb)
I photoshopped your pic to show you what is possible. When you do this in software, you will have a certain loss of image because you are pulling and stretching part of the image out of the picture boundaries. When I take photos of this kind I anticipate this and frame shots such as to allow me to do correction without losing important componants of the image. Or at least try to minimise it.
Cheers
You can also re-stump the house to level it.
(Just kidding)