Starbase 74 was a Federation Spacedock-type starbase administrated by Starfleet. The base orbited the planet Tarsas III in Sector 001, which was a region of space in the Alpha Quadrant. The starbase worked in conjunction with Starfleet Operational Support Services in the routine maintenance and upgrade of systems and replenishing of supplies aboard starships. This starbase was located near the Beta Magellan system. In 2364, the base was commanded by Commander Orfil Quinteros. (TNG: "11001001"; TNG: "Conspiracy", okudagram)
In that year, the USS Enterprise-D docked at Starbase 74 to undergo an upgrade to its computer systems, performed by a group of Bynars. The Enterprise was hijacked by the Bynars shortly after the upgrade began, and taken to Bynaus. The USS Melbourne was one of the three other starships docked at the time, but was unable to pursue due to repairs in progress. (TNG: "11001001")
In the first draft script of "11001001", this starbase was instead named "Armus 9".
At first, Starbase 74 was conceived as a new design of space station. To this end, Andrew Probert produced a couple of concept drawings to show how the facility might look, including such details as the "main gangway" and "umbilical" between the starbase and a ship docked there. (Star Trek: The Magazine Volume 2, Issue 12, p. 42)
Ultimately, however, Starbase 74 was depicted using recycled footage; for "11001001", the footage of the USS Enterprise-D on approach to Starbase 74 was stock shots from Star Trek III: The Search for Spock, showing the original USS Enterprise entering the Earth Spacedock in orbit of Earth, and the Enterprise-D was superimposed over the Enterprise to complete the shots.
Starbase 74 was also seen in A Klingon Challenge, a Star Trek: The Next Generation interactive VCR board game. As with the events of "11001001", the Enterprise-D once again gets hijacked from this starbase, this time in an attempt to start a war between the Federation and the Klingon Empire.