So you shot a nice image while on vacation from an impossible angle - couldn't step back any further, a tree was in the wrong place, whatever. This was the sorry result:
Correcting the verticals during raw conversion is step one:
After which you are left with this impossible result which, to say it nicely, has a couple of sizable holes in it in all the wrong places:
With some careful cutting and pasting, some cloning and healing, a lot of blending and a bit of content-aware fill, a passable image results:
Conclusion: image saved!