I had fun photographing street art in downtown Los Angeles in the Arts District yesterday. I focused on capturing windows and doors because that gave a sense of context. Shooting upward at architecture means there is going to be significant keystoning, or the angling inward of vertical lines. I usually don't like that, so I typically use either Photoshop or Adobe Camera Raw to correct that. In Photoshop, it's easy. Simply use Select > all, and then Edit > transform > distort. A box forms around the image, and by grabbing a hangle in any of the four corners, you can pull the image such that the vertical lines become more vertical.
In ACR, click the 'lens corrections' icon in the upper right section of the dialog box. Then, choose the 'manual' tab. Under the heading 'Upright, there are several icons you can choose from. Try all of them until you like what you see.
