The Yard was Starfleet's secret alien technology research station. In the late 2260s, it was commanded by Commodore B6 Blue (also known as "Bishop"), a Nasat who had urged Spock to enroll at Starfleet Academy.

The remains of the Doomsday Machine were sent to the Yard where they were stored and studied by the researchers present there. (TOS - Constellations short story: "Devices and Desires")

"The Yard" is a nod to the Philadelphia Naval Shipyard, where Robert A. Heinlein, Isaac Asimov, and L. Sprague de Camp did classified research during World War II.