It gets a little hairy when you're plotting cities in different countries, primarily because the US often has cities with the same names. A couple of options:
1) Geocode your data ahead of time so you can just plot lat and long.
2) Just add Country and City to the view. Tableau will make a good guess on a lot of the locations. Where there is a problem, you'll see an "Unknown" icon at the bottom right. Click on that, then select "Edit Locations" and correct the problems in red (be sure to address issues on all the tabs).
Thank you for your response. I'm trying to select the cities or country by mapping. However, the American cities became unrecognized if I chose European countries. How to fix the problem? Thank you very much .
Thank you for your help. This is a great idea. I'll try to do that.
Did it work ?
Thank you for your message. Yes, it works! Actually I particularly used the two cities' latitude and longitude in Europe , and input the measures in Tableau map built-in locating box, and finally get the locations of these cities in Europe.