Modern Colonnadeby
eloiseComment: In answer to your question: A crooked horizon is one of the easiest to fix of common photography mistakes.
Most cameras will distort the edges of a photo when using a wide angle lens. When the lens is zoomed out, it is in the wide angle range. It is disconcerting to humans to look at tilted horizons. An image that is 1 to 2 degrees off it's axis looks like an unintentional mistake. If you are deliberately tipping an image, the tilt has to be greater to look like you meant it to be part of the composition.
One way to make an image that has lens distortion appear straight is to balance the bending on each side. If both sides bend inwards the same amount, the image will seem to be straight. However the best way is to choose something in the center of the image where there is no distortion and make sure the horizon there is parellel to the edge. Obviously this is not always possible, but in your case you have the sign "Office Tower" in the dead center. You can rotate the image to get that sign straight.
If you want to use the wide angle aspect of your lens, it might be best not to choose a subject that has stark upright lines at the edges of the frame as it will emphasize the bending. If the edge is mostly sky, no one will notice it.
Part of creating a great photograph is learing the strengths and weaknesses of your camera and working WITh it rather than fighting against it. Everyone wishes his camera could do just a litle more.
ps..I think it is better to wait till the voting has ended to challenge a comment. Were you asking me to reevaluate my opinion of your picture and give it a better score?