École Spéciale Militaire de Saint-Cyr
I always wanted to pitch you the idea of the general staff wonder for a while since in my opinion it marks a big change in military operation/logistics/administration. Since the Prussian one is probably the most famous one I thought Scharnhorst or a pic of one of the Great General Staffs would do a good representation.
I also made a symbol for the imperialism government if you are interested.
Edit: Have you thought about adding wind farms/turbines? VladimirSlavik did some graphics: http://forum.freeciv.org/f/viewtopic.php?f=12&t=75568&p=81282&hilit=wind+farm#p81282