MedHammer 40,000 Locations
Solar System
Magna Terra
Just as the Imperium is a pathetic hobbling shell of its once proud glory, "Great" Terra, embodies this decay barely and tarnished glory barely weathering the decay of eons.
Terra was once a beautiful green and blue world teeming with life. Long ago during the Dark Age of Technology fantastic self sufficient hive cities were built to house millions of people. The humans that lived on this planet had destroyed its land and its oceans in the name of progress and later in the name of war. The Emperor tried to unite Mankind, to transform terra into the lush life teaming world it once was. But that dream is as comatose as he is.
Instead of renewal, Terra is a death world, completely destroyed by The Great Treachery and the actions of Alpharius. Its atmosphere burned away by Alpharius' bombing of the Imperial Palace. Fulgrim, the great Terraformer and Biologist had hoped to restore this atmosphere only to learn that Alpharius had seeded the planet with Ork Spores, as a final parting gift. These spores took root in the thin atmosphere of Terra and, while not having enough air to actually mature and develop, would still release hundreds of more spores before returning to dormancy. The centuries of Ork Spores begatting Ork Spores has resulted in the entire planet becomming coated in Oak Spores, some places only having a thin coat, others having a piles of spores several feet thick. Fulgrim was forced to abandon progress on terraforming, fearing that any further improvements of the atmosphere would doom Terra to an Ork infestation, all but impossible to face. So now Terra is bright green in cruel mockery of its former beauty.
As Terra is a death World, The Hive cities, the imperial Palace, and the Monuments are all little more than Planet bound satilites. And must now have to be supplied with Air in addition to Food and supplies. Addittionally, they now must be vigilant in their filtration and ventilation, and entry systems, less the trillions and trillions of Ork Spores make their way into the hive citties. As it stands several hive citties have fallen and needed to be reconquered and re settled following an ork infestation. Massive walls have been built around the hive cities in the hopes of protecting the cities from the spores and the Imperium regularly promethium bombs the planet, but these can only stem the tide against the ork spores. Ultimately Fulgrim and his Brother must find some sort of xenocidal way to eliminate the orks from terra once and for all.
In addition to the Imperial Palace and the Hive Citties several religions have Settlements across terra. Because the Imperium does not permit churches and temples on holy terra, these Settlements are "Museums" and "Schools." These museums, dedicated to some aspect of Terra's history function like primitive hive cities with millions working and living within them.
Luna
As Terra has waned, Luna has waxed to become the actual population and commercial center of Terra. Despite being a lifeless death world, Luna, does not have the issue of trillions of semi-dormant Ork Spores seeping into every hive world and coating the planet. Despite losing most of its Nearside population from Alpharius' bombing of the surface, Luna has rebuilt and has nearly three times the population of Terra. The Entire planet is covered with merchant hubs, settlements, and religious cities. Because of The Emperor's law on Terran religions still being in effect, most religious seats nominally located on Terra are actually situated on Luna. Most famously would be the Aurelian Cathedral of The Holy Martyrs located on the far side of Luna. As well as the "Final site of Pilgramige" a Terran pilgrimage site that is actually on Luna.
Venus
The impossibilty of Terra becoming viable again has encouraged Fulgrim to terraform the Sol Systems other planets. Venus represents Fulgrim's magnum opus. A green and Lush Garden World. The planet is exclusive to the Primarchs and upper echelons of Terran Society. Its major city "new chemos" is one of the few places in the Imperium that could be considered Magnificent and beautiful, and it is carefully monitored by its Primarch.
Moons of Jupiter and Saturn
Like Venus, the Moons have been encouraged into development in lieu of Terra. Unlike Venus, which is a lush private garden of Fulgrim however, The Moons are Crowded with citties and military fortifications.