Tranquility Base

From Memory Alpha, the free Star Trek reference.

Tranquility Base is a location on Luna, part of Mare Tranquillitatis ("the Sea of Tranquility"). In 1969, the area was the site of the first Human moon landing by Apollo XI’s L.E.M. Eagle. (TOS: "Tomorrow is Yesterday")

By the 23rd century, a Starfleet shipyard was located there. Among the ships built there was the USS Defiant. (ENT: "In a Mirror, Darkly")

According to the dedication plaque seen on the bridge of the Defiant; this is where the ship was constructed though never mentioned in dialog.