Gigantion is not the kind of place the Oracle would appreciate, but it's a nice, cozy home for a robot. The planet is a huge machine world, a vast analogue of Cybertron, but constructed mostly by its inhabitants. These Cybertronians, whose descendants have grown to tremendous size, settled on an Earth-like, rocky, organic-covered planet, and built their cities on it. As their skills increased, they continually rebuilt these settlements right on top the old ones, until the planet was completely enveloped in a vast series of constructed layers, complete with artificial foliage, simulated skies and day/night cycles - but at its heart, the original planet remains, well-preserved and even supplied with artificial light, but forgotten.
The titanic Transformers of Gigantion, large and powerful, are fortunately not much given to violence and warfare. Most are gentle and peaceful, desiring only to hone their skills and build ever grander structures. They work closely with the small Mini-Con Transformers, who can tackle the delicate tasks too refined for the heavy manipulators of their bulk comrades.
The dominant language of Gigantion is practically identical to a Scottish dialect of the English tongue. The Mini-Cons beep with a Scottish accent, no doubt. At the time the planet was re-discovered, it was led by the gigantic Metroplex.
According to Gigantian tradition, old cities are to be left alone. The population constantly moves to unbuilt areas, constructing new cities, never returning to the old ones. They even go so far as to dump the data on those old cities from their computers. Why this custom came about is lost to time, but it's tradition, and if you stopped doing traditional things just because they make no sense, then really, what's wrong with you?
The planet is surrounded not just by a ring, but by a debris field made up of the detritus of ancient building projects...and probably bits of a long-gone planet.
Gigantion was plotted out as one of the four worlds to serve as a focal point for the galaxy-spanning Space Bridge project. The starship Lemuria was sent to the planet, along with a Cyber Planet Key, but like the other colony worlds, was lost to time.
Unlike the other worlds, this one got even more lost, as at some point in the planet's ancient history, after the original colonists arrived, the entire system was sucked into a wormhole, transporting it to an alternate universe.For a time, the only way to reach this new universe was from a tunnel in time and space in the Skeleton Nebula, which was only open for a few days every year...though other methods have since been found.
There, the planet ran afoul of Planet X, whose warlike inhabitants wished to consume the world for its rich energy supplies and raw materials. The Gigantians turned to the power of the Cyber Planet Key, which caused both the planet and its inhabitants (save the Mini-Cons, of course) to grow to massive size, allowing them to fight Planet X to a standstill. When Planet X was detonated by one of its own malfunctioning weapons, peace returned, and the inhabitants of Gigantion went back to their jobs. Tales of the war were eventually lost to the centuries, being little more than rumor and myth to its modern inhabitants.