Atlantis (Stargate) based on Atlantis
Ancients
The race of the Ancients is first mentioned in the Stargate SG-1 season 2 episode "The Fifth Race" as the original builders of the Stargate network and members of the former Alliance of four great races. They were considered humanity's predecessors, originally establishing Earth as their homeworld after they migrated to the Milky Way, and having seeded multiple galaxies to allow life to evolve on uninhabited worlds. At the time that the Stargate franchise takes place, the Ancients have long since "ascended", i.e. they shed their physical bodies and live eternally as pure energy on a higher plane of existence with an increased power and capacity for learning. While they are no longer physically present in the universe, their highly advanced technology—including the Stargate—remains behind, all of which has shown to be almost entirely resilient to the decay of time, and has also proven to be the most advanced technology anyone has ever encountered. With humans from Earth as their closest descendants both from a genetic standpoint and an evolutionary standpoint, they have shown the most proclivity in utilizing Ancient technology when they encounter it.
For the first six seasons of Stargate SG-1, the ascended Ancients maintain a strict rule of noninterference in mortal affairs of the material galaxy, and the interactions between humans of Earth and the Ancients are restricted to the outcast Ancient characters Oma Desala and Orlin; the Ancients' ascension was also used as a plot device for the departure of actor Michael Shanks (Daniel Jackson) in season 6 of Stargate SG-1. The fictional background of the Ancients was extended with the franchise's Atlantis mythos that began in the Stargate SG-1 season 6 finale "Full Circle", and which also served as the basis for spin-off show Stargate Atlantis. The Ori arc of Stargate SG-1's seasons 9 and 10 expanded the Ancient mythos further.Atlantis
The pilot episode "Rising" of Stargate Atlantis establishes much of the backstory of Atlantis: The city was built by the Ancients millions of years ago, originally as a central outpost in prehistoric Antarctica, until an unexplained crisis—involving a virulent plague—forced them to relocate the city to the planet Lantea in the Pegasus Galaxy via intergalactic hyperdrive engines. The Ancients (known as "Ancestors" to the denizens of Pegasus, and "Lanteans" to the Wraith) seeded several human populations in the Pegasus galaxy, but rarely interbred with them. As explained in season 1's "The Defiant One", the Wraith drove the Ancients from their holdings until only Atlantis was left, defended by its powerful shield and a network of armed satellites. The Atlantis Expedition learn during their arrival in Atlantis in "Rising" that the Ancients submerged the city in Lantea's ocean to evade detection by the Wraith and returned via stargate to Earth, where survivor recollections formed the basis for the ancient Greek accounts of Lost City of Atlantis. In the Atlantis series finale "Enemy at the Gate", Atlantis returns to Earth and lands in the Pacific Ocean near San Francisco.The producers intended the city of Atlantis to be the size of Manhattan.: 251  Many sets used for Atlantis are part of a large sound stage that was built for almost US$2 million. This stage is used for rooms like the brig, several balconies, and other interior parts of Atlantis. Green screens were used if an outdoor view was required in an episode. According to digital effects artist Bruce Woloshyn, the series' original CGI model of the city of Atlantis was over four million polygons, which was feature film in size. This allows the city model to still look good and detailed in extreme close view. Since most of the city is modelled rather than textured, the details appear more realistic when the virtual camera revolves around the city model.