Try to name the most populous urban areas that contain each letter for each continent with the help of a map. In order to prevent any one large city from taking several letters, each city will only be used once according to which letter appears first in it's name.
For example, if Oslo was the largest city in the Europe that contained the letter O and the largest city in Europe that contained the letter S, it would only be used for the letter O as it appears first in the name, and the next largest city to contain an S would be used.
Only incudes cities with a population of at least 1 million, except in Oceania, which uses cities with a population of at least as 250,000.
Some loosely defined regions have been filled in for you. None of the letters in the word "city" are used.