Why does the horizon look like it's curved? I've noticed before that in some photos I take things that I thought were perpendicular to the ground (i.e., pillars, columns, etc.) have looked like they've been bending, too.
Actually, here's an example:
The columns towards the left look like they're bending to the right, and the ones on the right are doing the opposite?
Could something be wrong with my lens, or am I missing something?