Barrel Distortion

You can fix photos suffering from barrel or pincushion distortion using Edit | Adjust | Barrel Distortion [Ctrl+Shift+D].

Barrel and pincushion distortion are frequent lens defects that have unpleasant effects on photographs of architecture and objects with straight edges. Use the slider here to set how strongly the photo's contents should be "pushed in" or "pushed out." When correcting barrel distortion, the Auto-crop option here is quite useful. You can set a quality level for this function; this sets what algorithm is used by the function. The low-quality but fast Nearest neighbor method is good while seeking the right amount of correction to use. The high-quality but slow Bicubic method is best once you are ready to apply the correction.

You should remove barrel or pincushion distortion from a picture before making any other edits to it
(and especially before cropping it or correcting collinearity or perspective).