Vis Uban, Ancient for "Place of Great Power" and designated P4T-3G6 by the Tau'ri, was the name of a city built by the Ancients in the Milky Way. According to notes of Dr. Daniel Jackson the city was intended to be the crown jewel of the Ancient domain in the Milky Way. However, a Plague soon broke out and the city was forced to be abandoned. If completed, it would have been more powerful than Atlantis. Based on this information, Jonas Quinn speculated that Vis Uban was the Lost City that Stargate Command was searching for, determining its Stargate address as the last on the list of new gates that Colonel Jack O'Neill entered into the gate map from the Ancients' Repository of knowledge. SG-1 led an expedition to search the ruins on the planet, where they located a deascended Daniel Jackson. Because of the plague forcing the construction of Vis Uban to be stopped and later abandoned SG-1 found only ruins of an incomplete city, which would have been the greatest and most powerful asset in the entire Ancient domain.
A thorough search of the ruins revealed no evidence of advanced technology and Jackson concluded that it was not, in fact, the Lost City. Jonas, then, thought to use it in a ruse to draw Anubis into an ambush; SG-1, working in concert with the Tok'ra and Goa'uld forces under the command of Lord Yu, sought to disable the primary weapon on Anubis' mothership and then destroy the ship. To this end, the planet was evacuated and a makeshift F-302 fighter-interceptor launch strip was built on the surface. Although Yu's forces failed to take part, complicating the plan, SG-1 succeeded in destroying the weapon on Anubis' ship. (SG1: "Fallen") Due to the knowledge that the Ancients could shield technology even to the most intensive of scans, it is therefore possible to summarize that there may be some technology located at the build site of Vis Uban possibly in hidden chambers or underground.