Marsbase was one of the earliest Human settlements on Mars.

As of 2045, it was the location of University Hospital, where Dr. Sally Bellero was Assistant Head of Psychiatry. (TOS novel: Strangers from the Sky)

the planet Mars
cities and settlements	Ares City • Bradbury City • Bradbury Township • Burroughs City • Cochrane • Endurance • Gunderdottir's Dome • New Venice • Nova Ares • Phillipstown
regions and provinces	Amazon Planitia • Martian Colony 3 • Utopia Planitia (Nova Ares • Utopia colony)
geography	Arisia Mons • Olympus Mons • Terra Strenum • Valles Marineris
bodies of water	Copernicus Lake • Lake Mlarcovik
outposts and installations	Fort Kiley • Fort Lincoln • Marsbase/Mars Base • Utopia Planitia Fleet Yards (Utopia Planitia Control • Utopia Station One)