Terra - Geography: Terra in the 41st Millennium is an Imperial Hive World, the largest in the galaxy. The Earth was stripped of all forms of natural resources many millennia ago; its soil is utterly barren and its atmosphere is now a fog of industrial pollution. Massive, labyrinthine edifices of state sprawl across the vast majority of the surface.What remained of Terra's oceans after the thermonuclear wars that scarred the planet during the Age of Strife boiled away in the years after the Horus Heresy due to the immense heat produced by the hundreds of billions of people who have been compressed into the world's limited living space. All liquid water to meet the Terran population's needs is now delivered from orbit by freighters who take large ice-bearing comets from the outer Sol System and bring them into Terran orbit to be melted down and dispersed to the population.Many mountain ranges have been leveled -- perhaps all but the Himalazian range (the Himalayas), which remain untouched due to the genetic engineering laboratories said to lie beneath them where the Emperor created the Primarchs and the first Space Marines after the Unification Wars more than ten millennia ago.The chambers of the Astronomican also course throughout the whole mountain range. Despite being devastated during the Horus Heresy and by the terrible wars fought across the surface of the world by the nations of techno-barbarians during the long Age of Strife, Terra is still the most vastly-populated and built-up hive world in the Imperium. Beneath countless layers and millennia of urban accretion, catacombs hold older cultures radically different from the surface ones.Much of the population of Terra exists in the most terrible squalor, their greatest hope that one of their offspring might be accepted into the Adeptus Terra, the Priesthood of Earth and bureaucracy of the Imperium, as a Menial, an Adept of the lowliest sort.A square metre of land on Terra costs more than a palace on any other Hive World; only the most wealthy citizens can afford to own a small section of land. Terra's entire surface, with the exception of the Antarctic region, is covered in labyrinthine edifices of state, including the Imperial Palace, the Ecclesiarchal Palace of the Adeptus Ministorum and the many departmental headquarters of the Adeptus Terra, the Imperial government.The headquarters of the Imperial Inquisition on Terra lies beneath the ice caps of the southern polar region of Antarctica and is one of the most secure installations in the entire Imperium.Terra was also originally home to the massive concentrations of industry known as "Orbital Plates," which in earlier times were referred to as "space elevators." By the time of the Great Crusade in the 30th Millennium most made use of anti-gravitic technology and no longer had any need to be anchored to the planet's surface.These orbiting cities were old even in the time of the Unification Wars, but during the Horus Heresy, in the years before the start of the Siege of Terra, the Primarch Rogal Dorn, who had been named Praetorian of Terra by the Emperor and was thus in charge of its defence from Horus' invasion, had them all dismantled, moved, or abandoned over questions concerning their safety and loyalty.In the 41st Millennium there are still countless orbital defence platforms circling Terra, and the Throneworld is the most heavily fortified and protected planet in the galaxy.