It's a stitch, using Microsoft ICE. And yes, I had to correct a few things. It was originally in color, and it was an HDR made with Luminance HDR. I then desaturated it in GIMP, and adjusted brightness and contrast to fit B&W. Finally, I copied a layer, and applied unsharp mask to the bottom layer. I then set the top layer to 50% and then flattened the image.
Pentax KP. I don't remember the specific settings, except it was f8.0.