Subdomain based filter

Hello,

I would like to build a website with local and general content. It is something like lasvegas.mycity.com, sanfrancisco.mycity.com in this way there is a subdomain for each city. Each website shows content related to the subdomain’s city and general content like faq and so on. It would be great to have a central user management.

I was already reading a lot about the thing but the more I read it gets more confusing than everything else. I was thinking about multisite, buddypress, … but at least I have the feeling that both all things are not what I am searching for.

Could someone bring some light into the darkness?

BTW: It is nearly the same like: https://premium.wpmudev.org/forums/topic/how-to-use-subdomains-as-filters-mu

Thanks a lot,
Vanessa