From publisher blurb: A Guide To The Megastructures of Science Fact and Fiction Want to populate your science fiction setting with memorable places and structures? Then this is the guide for you. Disks, Rings, and Spheres takes a deep dive into science fictions “Big Dumb Objects” (or “BDOs”). The 31 items listed in this product range from the terrestrial (such as self-contained arcologies), to the stellar (such as ringworlds), and beyond. In addition, not only is a brief history of the object given, but also notes on how it is created, and how such a BDO can be used on your campaign.