Travel to the southwestern-most vigilantes in the poor district of Damascus. On one of the buildings around them is a outcropping in the wall. Climb on it and you will see that it looks exactly like G1 Optimus Prime in vehicle mode. Note that there may be more than one outcropping in the area, so look carefully. If you lose sight of the vigilantes, you have gone too far. Also, these types of structures can be found throughout the poor district.