This shot was of the rotunda room in the Bing Wing of Green library. The verticals in this scene (the columns) converge to a point just outside the picture. To get this effect, I shot at 14mm focal length (giving an ultra-wide view) and pointed my camera up. I used a portrait orientation to get a sense of the vertical height in the room, and to get both the floor and ceiling in the view.

I shoot at ISO 800 with 1/80sec shutter, which was more than hand-holdable. I actually used the Auto-ISO feature on my camera to set the ISO, while I defined the aperture and shutter speed. F/5.6 was used to get some DOF margin (and reduce unwanted effects like vignetting you get wide-open), although at such a wide focal length, having enough DOF is not a concern.