Open the sp_yourcityname_homecity.xml file located in 
\My Documents\My Games\Age of Empires 3\Savegame (dont forget to make a 
backup of this file) find this line [skillpoints).
The line should look like this [skillpoints)xx[/skillpoints), where x is 
the number of skillpoints you currently have. Change the xx to a high number 
such as 999, save the file and start 
Age of Empires <http://www.chaptercheats.com/cheat_display/16078.htm> 
3. Go into a skirmish game, go to manage your city and you will now have 999 
unlock points to unlock various things for your city.
Submited by Tan Bui