- "It talks about a city of the Ancients called Vis Uban as being a place where the Plague began. This was going to be the crown jewel in the entire Ancient domain. Only it was still under construction when the Plague broke out."
- ―Jonas Quinn
Vis Uban, Ancient for "Place of Great Power" and designated P4T-3G6 by the Tau'ri, was the name of a city that the Ancients built in the Milky Way. According to notes by 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. Based on this Jonas Quinn speculated that Vis Uban was the Lost City that the SGC was searching for, determining its Stargate address as the last on the list of new gates that 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 descended Daniel Jackson.
A thorough search of the ruins found no evidence of advanced technology, and Doctor 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 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")