For many, the most likely place in the Solar System to search for life beyond the Earth is Mars. This lecture describes the properties of Mars, a desert world with a thin, dry, cold carbon dioxide atmosphere. I will review evidence that has begun to point unequivocally to the conclusion that Mars had flowing and standing liquid water on its surface in the past, perhaps during the first billion years or so. If Mars had a warm, wet past, did life also get a start there? Recorded live on 2009 Oct 30 in Room 1005 Smith Laboratory on the Columbus campus of The Ohio State University.