Habitation spheres were known to orbit Imperial Center during the highpoint of the Galactic Empire. They were usually found in orbits above that of skyhooks.[2]
According to a report by Pollux Hax, two giant-sized habitation spheres were constructed in orbit of Coruscant by the planet's great space construction platforms, around the time of the Battle of Endor.[1]
When the New Republicconquered Coruscant a few years later, these structures were apparently no longer present.
The artwork depicting the habitation spheres was originally concept art for an early story for Star Wars Episode VI: Return of the Jedi, in which two Death Stars were being built in orbit of the capital planet of Had Abbadon. As a result, one of the habitation spheres even has the recessed dish on its southern hemisphere where a superlaser would be located.
The manner in which Pollux Hax discusses the spheres, insisting that they are being assembled "strictly for peaceful purposes," suggests the possibility that just the opposite is true—that these may have in fact been further Death Stars early in the process of being built. This supposition is often cited as a source for a third Death Star depicted in the Star Tours ride.