Massyleon
Massyleon is the capital world of the Massylean sub-sector and possibly the most populous world in the wider Eridani Sector, rivalling even sector capital Saedra in terms of economic importance. Inhabited by humans since the Dark Age of Technology, the planet has become a hive world entirely incapable of feeding itself. Its biome hasn't entirely collapsed, and the air remains reasonably breathable (by hive world standards at least).
Historically, Hive Massinissos was the capital, and has always been the largest hive. As its factories belched out ever more fumes, its ruling elites emigrated to the clearer air of Hive Zantium, and in time, the smaller hive became the planet's true seat of power on the planet. The Salican Palace was built in Zantium as a new governorial palace during mid-M37, and the hive has been the capital ever since.