This is the most beautiful place in Casablanca, hands down. If you are in the city and don't go to see it, you're missing out! The location of the mosque is right on the water and the architecture is striking.
Plan out a time to go on a tour inside though. There were no tours when we went, so we missed out.
Also, there were traffic blocks up that didn't allow us to walk all the way around the buildings, so that was a little disappointing. Nonetheless, it's beautiful, and I felt lucky just to see the parts of it that I could.