I don't know how you could use to Tableau to get the source data actually structured that way, but you can make Tableau display the data fairly close to your screenshot. Check out this view: If you put Pivot Field Names on Rows, and Pivot Field Values on the Marks card as text, it will list out the values. There's no comma between values though.
Check out Sarah Battersby 's response in this thread Map Tooltip Multiple Values Showing * where she used a Table Calculation to list values in a field separated by a comma. This was in a Map Tooltip. Maybe something here will apply to displaying your data as you wish (it still won't structure the underlying data with City's listed in a single cell, but I'm guessing you're more concerned about getting the display right).