Which way is up?

It only takes a moment to sense something off kilter with this shot.  Notice how all the buildings slant to the right?  This image needs counterclockwise rotation.  Many rotations are easy; this one isn't.  The photograph has mild perspective distortion.  No matter how one rotates it doesn't feel correct because the verticals on these buildings aren't quite parallel.  Also the sidewalk slopes upward from left to right.  Decreasing the slant on the structures means increasing the slant on the sidewalk.  So unless an editor is very careful about which cues to follow, something is going to come out wrong.

It helps to know that this is the Brooklyn Daily Eagle storefront, photographed in 1916.  Most of Brooklyn development occurred between the American Civil War and World War I.  This was relatively new construction when it was photographed so we can discount the possibility that significant shifting or settling would have altered the buildings themselves.  Let's look for trustworthy points of reference within the image.

The man descending the stoop uses canes, so he might not stand upright.  But what we can depend on is that the steps would be level.  Looking closely at the base of this stoop confirms my suspicions about the sidewalk: notice how the base at the left edge of the stoop is nearly twice as long on its left side as on the right side. This was compensation for sloping terrain.

Here's how that stoop appears after rotation and spot removal.  These weren't the only lines of reference when I rotated; I also went by the building verticals and roughly split the difference in terms of angle distortion.

Here's a glance of the whole image after rotation, cropping, and several lengthy rounds of dirt and scratch removal.

It's better than things started, but the distortion still leaves an uncomfortable sense that the lamppost is going to keel over onto something and the French restaurant at right looks as if it is leaning into the Eagle offices.  This keystone effect is subtle, but it's there.  The solution is to perform a mild perspective crop.

Here's the end result.  Added a touch of curves adjustment to bring out contrast in the midtones, plus localized brightness and contrast corrections.  The automobile at far right no longer fades toward the edge of the frame.  Let's hope those ancient cars had good brakes because the driver didn't angle the wheels toward the curb.  Otherwise, nothing looks askew.