Before I start designing my city logo, I did some research on how other designers design city logo. Here are some logo I found online.
The one in the right button is from the designer Aaron Draplin. The marten in the right button with waves and building is the logo he designed for his hometown. I watched his video about how he comes up to this idea. The video is very thought-provoking.
Through study from these designs, I found that most of the city logos use a landmark building as an icon of their city.