Academy at Mare Nubium

From Halopedia, the Halo wiki

The OCS (Officer Candidate School) Academy is where UNSC Naval personnel begin their training as either conscripts or volunteers. Their training ranges from multiple branches, including ship piloting, and officer training.

Graduates from Luna OCS Academy include Ensign William Lovell and Lieutenant Dominique.

File:Lunaacademy.jpg
The Luna OCS Academy seen from inside.