Robert--I think I can get you started. Someone more knowledgable can fill in the details. In ages past an Indian tribe from Mexico was told (by the gods?) that when they found an eagle with a snake in its mouth and sitting on a cactus--this was the place they were to build their city. They roamed around for a long time sure they would never find such an event. They finally found all of the conditions in the middle of an island in the middle of a lake. They built their city their--it became Mexico City. This symbol is in the middle of the Mexican Flag. Sorry--can't help with the other side. Doug