Question about wallpapering

I'm trying to wallpaper the top level of my townhouse, but there is one segment of wall that I just can't seem to reach. The one directly behind the stairs.

Is there a way to get to that spot; a sweet spot I need to find, or will that one segment be bare forever?

Is there a way to get to that spot; a sweet spot I need to find, or will that one segment be bare forever?