I am not sure why you will need city-based icons set, but there is already a solution for this. If you need city-based icon sets, you can try City sets.
This new project is still in very early stage and only added icons for London, New York, Paris and Sydney. This is an ongoing and ever-expanding collection of free vector icons. So, we can expect it to add more cities soon.
This project has been created by London-based Digital Designer — Bryn Taylor.
All these icons are free to use with no restrictions. So, you can use these icons even in your commercial projects.