The Emergence of Man is an older series from the early 70's. I currently own all of the 20 volumes (the index is paperback and I don't really consider it a volume, per se), and in general I think they're pretty good (though some of them are a bit dated now). Each volume deals with one of the precepts of civilization or one of the civilizations that emerged at the dawn of humanity, and as such, they offer a unique glimpse of what life might have been like for our earliest ancestors.
Two things to watch out for, though; first, some of these volumes have differently colored spines depending on which printing they are from. If you are looking for a aesthetically pleaseing set, make sure they are all the same printing and color! Second, there is a paperback master index with this set. I didn't include it in the volume list, but if you are looking for the complete set, you should try to find the index too.