Atlantis (OU city-ship)
Atlantis was a city-ship created by the Great Beings, located on the planet of Lantea. Naju was exiled from it.
Many many years later, the city was taken over by humans from the Atlantis Expedition, including Elizabeth Weir, John Sheppard, Rodney McKay, Ronon Dex and Axel Storm.
Naju then tried to return to the city. Despite Orlin disabling his ship, the Enterprise, he succeeded, and used its Stargate to arrive at Darkmount.
Later, it was randomly teleported somewhere else by Ta'harok. Everyone promptly forgot about this.
The city was then attacked by Blackout's forces, who wanted its technology. However, they were unaware of the humans now inhabiting the city, and the Battle of Lantea began. Blackout personally teleported into the city and tore his way into the control room. Despite many people getting in the way, Blackout took over Atlantis and used it to attack the Wigwam, and then ran off, took apart Atlantis, and used the parts to expand Darkmount.