There are a variety of things that I really like about Cartagena, Colombia, but the photography opportunities are right up near the top. The old part of town is divided into three districts, all within the massive, old city walls. If you are coming here, I highly suggest you stay at a place within the walls and there are dozens upon dozens to choose from.
What makes Cartagena a great photography destination is the color. For whatever reason, the particular form of color that I love in my photography is the combination of bright and vibrant colors combined with a bit of decay and disuse. The juxtaposition is one that I find fascinating.
And Cartagena has no shortage of spots to shot those contrasts, literally all over the old town. I hope you get a chance to visit some day.