The Terran Protectorate Stellar Navy headquarters is actually three massive space stations. The most noteworthy and famous is Fleet Headquarters, the largest human anchorage ever built with 16 births capable of docking even capital ships, including two attached capital-class shipyards. It has numerous docking bays for frigates and pinnaces, houses 6 full wings of fighters and has the firepower of a half dozen battleships.
In addition to the anchorage, there are two sky cities nearby; one housing naval high command and the other housing the Stellar Naval Academy. With Home Guard, the equivalent of two battle fleets, guarding the Terra Nuevo system, and hundreds of ships routinely in attendance, plus the planet's ground-based defenses, the headquarters of the Stellar Navy is not considered impregnable, but it is considered too costly for any enemy to realistically consider a viable target.