I'm afraid to say, I didn't completely follow the assignment. This is not my favorite place-- it's more like a place that intrigues me--which goes to show that you are free to bend the rules!
I chose to illustrate this market because it was always a place that fascinated me while I was living in Cartagena. It's chaotic, grimy, colorful, and whenever I passed by the market on the bus, I noticed that everyone would plug their nose. It's the place to go if you want to experience local culture in Cartagena, beyond the touristic zones. But I'll warn you--like everyone has warned me--bring your tiny purse and nothing more.
Here's a photo of my brainstorming. I also wrote out a list of some other ideas: