Terra itself is a sprawling hive world, its surface utterly infertile and covered with dark, towering spires of iron, colossal gothic cathedrals, ancient ruins, and masses of pilgrims come to the cradle of Mankind to pay homage to the God-Emperor. Its oceans have long since boiled away, and beneath the countless layers of metal and stone that have built up over the eons, Terra is a lifeless ball of rock.
The terraforming of Mars had begun in the earliest days of the golden age of man's expansion to the stars, bringing new life and hope, but in the end, this was a remission, not a cure. Within the span of a few centuries, the planet had died its second death, choking on the fumes of volcanic forge complexes, continent-sized refineries and the effluent of a million weapons shops.
Our planet is an interminable metropolis that twinkles with power systems, city lights, traffic landing beacons. Seen from orbit, Imperial Center is a blaze of light and sparking colors, reminding some spacers of gemlike corusca stones, after which this planet was named long ago.
—Pollus Hax, The Illustrated Star Wars Universe
Layers upon layers of urban sprawl eclipse the globe's crust, and it is done.
Scant few years have passed since the start of this grand project, but it is already difficult to recall what the surface of <planet> was like. Verdant? Rugged? It is all steel now, miles in every direction.
A place once molded by chance and the unthinking laws of nature, now a design wrought from indomitable purpose.
The surface of Nar Shaddaa was an interlocking grid of miles-high cities and docking stations, built up over thousands of years. Level upon level of freight depots and warehouses and repair facilities ere linked by gaudy old thoroughfares that spanned the globe, bridging canyons that reached from the upper strata, swarming with life, to the glowing depths where several forms of subspecies thrived on the refuse that fell continuously from the towering heights.