This is a steal / riff on Asher's correct answer, imo.
If you are using a tablet, tilt it so that the left hand side is closer to your face, now does it look ok, ........on my cheap tablet it does.
EDIT
In case his comment is deleted, please take account of Samuuel Weir's remark in assessing my wording below:
I don't think that it's a matter of lens distortion. As I recall, it's an apparent distortion primarily due to the fact that the plane of the camera's sensor is tilted upward with respect to the horizon. There are so-called "perspective control" lenses which can correct for the distortion. See, for example: kenrockwell.com/nikon/19mm.htm . Also: en.wikipedia.org/wiki/Tilt–shift_photography (Sorry, it doesn't appear that the entire web address was converted into a hyperlink because of the hyphen. Just copy the whole address and paste it into the address line of your browser
And tfb
I agree with @SamuelWeir I think, although I originally thought the barrel-distortion reasoning was really good: it's more likely to be perspective distortion due to the sensor plane being angled upwards. Although the image is missing any useful EXIF data and the person didn't tell us what camera it was taken with, many modern cameras, if they know enough about their lens will, when creating JPEGS, correct for the distortions they know about. So if this was taken with such a camera, it seems unlikely you'd get so much lens-related distortion.
Both of these users have a much better grasp of physics than I do.
END EDIT
No building authority (except Pisa Municipal Council in Italy) would allow this degree of vertical tilt, so obviously the camera does sometimes lie.
This is an example of aberration, caused by distortions of light ray paths inside of the camera lens, particularly with zoom lenses.
This curvilinear aberration can take one of two forms, either like this:
Pincushion distortion:
Or like this:
Barrel distortion, which is what causes the effect in your picture.
These pictures are taken from Curvilinear Distortion.
PhotoSE deals with this, but on first reading anyway, not in as much detail as I would have expected.
I agree, if it was due to a previously unknown aspect of physics, that would be great. Sadly, it's more mundane.