Rarely I will 'edit' my photographs. I think it's only been of recent that I've been a bit more critical in analysing my work. From a technical point of view, in this case wide angle lens distortion. It would be wonderful to invest in a more complex photographic apparatus, but with a few tweaks (occasionally) you can correct any technical errors (mostly). The alternative is a tilt-shift lens. There are so many options for both film and digital, but for now, I'm sticking with what I have.
In the example below, is the original image photographed with a 28mm Prime lens. You'll notice around the edges there is a slight twist. Starting from the centre and heading outwards, the image bends. This is due to the natural distortion from the lens. The lower the number, the wider the angle of view is, and vertical lines will generally distort as you get closer to the edges. Hence why it is often recommended not to photograph close-ups of people with a wide (less than 50mm) lens as you'll get a 'fishbowl' effect. Sometimes this can work if that's is what you're aiming towards artistically, however in this case, I opted for something a little more 'optically' correct. This can be adjusted using 'lens correction' in Photoshop CC.
Most the time I enjoy using a wide lens for architecture and finding a 'line' to use as a reference point / guide for the final photograph. In this case, a wide lens is perfect. Much practice.