From Halopedia, the Halo wiki
Mare Nubium is noted to be cratered, crossed by tunnels and surface tubes connecting areas of human habitation. The State of Mare Nubium is divided into a number of counties, including the County of Newton which is the location of the Asimov Center. It is also the location of the Academy at Mare Nubium, an important UNSC Officer Candidate School. The State of Mare Nubium Department of Health issues Certificates of Live Birth for all persons born in Mare Nubium.
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