Just something on my mind.. Say some group of beings has already conquered the galaxy, lived for millions of years, and then forgotten about us or died out. Is it possible that thye or somebody else has planted some sort of recognition system on Mars or a Moon to detect when other beings come to the planet? And then terraform it to those beings standards? Just a thought (After hearing about Mars's heating up a week ago, and now the Mars Orbiter has found water ice all over the surface..)
While I'm in no position to have an opinion on the subject I would like to say that it would be pretty cool if that were the case. Its funny that we often say that it may be our job to plant the seeds of life throughout the galaxy: When another civilization may already have a step up on us. It makes great for great daytime reverie.