Return a List of string and append/concat a List in C#

Got this from stackoverflow - http://stackoverflow.com/questions/1036829/how-to-return-list-of-strings-in-c

public static List<string> GetCities()
{
  List<string> cities = new List<string>();
  cities.Add("Istanbul");
  cities.Add("Athens");
  cities.Add("Sofia");
  return cities;
}

To append to a List just do something like this
List<string> thumbnails = new List<string>();
thumbnails.AddRange(--------have a string array here--------------);