Mars Needs Women is probably the single most-played network map ever made - even when considering games other than Marathon. In the days of the first appearance of Marathon (and I'm talking about the leaked beta that pre-dated the demo) there was only this one network map. Then the official demo came out and it too had only one network map - Mars Needs Women.
When Marathon II: Durandal came out it would have seemed as though Mars was only a fond memory. However, after being reprised in Marathon Infinity with new textures, Mars enjoyed a resurgence.
Now in the twilight of the time of Marathon, Frogblast: The Ventcore Project is giving this progenitor of network maps new legs by bringing it to UT.