Storing The Contents Of A AutoCompleteSource (HistoryList) In a String

All I am simply trying to do is display the AutoCompleteSource.HistoryList in a message box. All the following code does is display the words HistoryList. How can I make it actually show the URLS of the HistoryLIst, in other words I want the contents of the HistoryList to appear in the MessageBox.

string s = AutoCompleteSource.HistoryList;
MessageBox.Show(s, "History", MessageBoxButtons.OK, MessageBoxIcon.Information);