I know, this is the same answer, that The Fern has already given, but I cant resist:
even after a second look, its either a Tree or a House Sparrow (ignoring size of the bird, which seems to be smaller than a Blackbird at least):
Following points makes this an House Sparrow imo:
-sleek build (enhanced by posture in this single picture) with long tail
-dirty, but pure grey underparts (in Tree Sparrow normally browhnish or buffish tones or more rare whitish tones
-better head pattern for this than for a Tree Sparrow. I think the dark ear-covert spot would either be visible or would produce a different pattern in a picture of this quality (no offense).
I know, I have been fooled by a similar picture just a few days before, but: even after a second look, this picture doesnt seem one for quiz-modus imo, just a low-resolution + bad artefacts picture. Reason? Dont know, but I still get the feeling that this bird can be identified with the necessary confidence as a House Sparrow, when location is taken into account.
Just a slight caveat: is the "head" of this bird real or a hole in the wall behind the grey-headed, dark-eyed bird? No, its a House Sparrow imo, agree with The Fern.