The Luna Shipyards were a Federation shipyard facility in the Sol system, in the vicinity of Luna, Earth's moon.
They were a functioning shipyard as early as the mid-23rd century, when they constructed the SS Xhosa, a fact listed on her dedication plaque. (DS9: "For the Cause" set decoration)
Luna Shipyards was never mentioned in dialogue, but on the dedication plaque of the Xhosa. Since the Xhosa was a civilian vessel, it is unknown if the yards also constructed Starfleet starships. It is also unknown if they were related to the Tranquility Base shipyard.