Gas giant habitat

Also called Bubble habitats, these are artificial habitats that float in an atmosphere, usually of a cool gas giant or ice giant planet. The structure is held aloft by an envelope of lifting gas (typically pure hydrogen), the 'bubble'. Shapes vary from gigantic balloons or airships or dirigibles of Type 0 civilizations to solid but lightweight spheres in Type I civilizations.

They would typically have nanobot technology for self-repair and be built near refineries for easy access to gas energy. This would form part of an interplanetary transportation system to get natural gas resources back to industries on planets and moons.