How to implement correctly on the site of the city?

Question

Search Engine Optimization

There is a construction site where all the content is specific to the day of each city, and it became necessary to switch the site between different cities.
Here are the options that I came up with:
1) www.msk.site.ru, www.spb.site.ru, www.site.ru - displays content for all cities at once
2) www.spb.site.ru, www.site. ru - displays the content of the city assigned by default (for example, Moscow)
3) www.site.ru/msk, www.site.ru/spb, www.site.ru - displays content for all cities at once
4) www.site.ru /spb, www.site.ru - displays the content of the city assigned by default (for example, Moscow)
That is, in fact, two questions, do the site or the city on subdomains be included in the first segment of the line, and the second question is what to display on the main page - the default city or content for all cities?