See all the pictures here.

Canon doesn’t have many ultra-wide choices: 14L, 16-35L and 17-40L. I have owned the two latter. The 16-35L used to be one of my favorite travel lenses. Especially on the 1.3 crop body. It has since been replaced by the 24L but I still love the dramatic wides the 16mm can produce. There is the usual slight distortion at wides but I found the colors up to par for L lenses and above average sharpness. It has a nice weight and a very solid feel.

Canon recently came out with a II version of this lens that is supposed to be sharper and control flair better. I am sure this is true but the huge lens filter and my satisfaction with the current version has kept me from upgrading. If you have the money, get the 2.8 version. If not, the 17-40L performs just as well… just not as fast.