The open orbital frameworks in which Starfleet builds, refits and repairs its ships, seen around successive Enterprises from the 22nd century to the 24th.
A drydock is a cage-like structure in orbit that surrounds a starship while it is under construction or repair, giving access for work crews, pods and lighting. The best-known example is in Star Trek: The Motion Picture, in which Scott takes Kirk on a slow tour around the refitted Enterprise in Earth orbit; the ship leaves a similar dock in Star Trek II: The Wrath of Khan.
In Star Trek Generations the Enterprise-B sets out from drydock on its maiden voyage. Next Generation episodes such as Booby Trap show the Enterprise-D taking shape in the docks of the Utopia Planitia yards above Mars, and Voyager is seen there before launch in Relativity.
The prequel series Enterprise opens with the NX-01 in an orbital dock above Earth, and the 2009 film Star Trek shows the fleet leaving a large orbital facility of the same kind.