Forerunner wealth

"Of course our family’s homeworld had changed little. What need for change when every square meter of its surface had been built upon, tuned, and adapted to Forerunner comfort and ambition? Even from a thousand kilometers, the arc of the planet’s limb was visibly ruffled with architecture, though certainly not the equal of the ruins found on any great Precursor planet—no vaulting orbital bridges stretching from world to world, no unbending and eternal cables.…

I had once taken a youthful fancy to our elevated oceans, each a thousand kilometers in diameter and a thousand meters deep, shining like a belt of overlapping coins around the equator. Each was separated from its neighbor by several hundred meters of elevation, their overlapping depending on whether cascades of water or twisting water-spout funnels joined them. Lifeworkers by invitation had for many centuries come to study these great aquariums and experiment with new varieties of exotic creatures, which they sometimes exported to other research groups and hobbyists across the galaxy." (Halo Cryptum; Ch.28)