Giant glass dome (InstanceTopic, 6)
From Compile Worlds
A giant glass dome is a construct often hypothesized to support human life in an otherwise uninhabitable climate, such as on the ocean floor or on other planets such as Mars. Unsurprisingly, none have ever been built, probably due to the enormous expenditure involved. It's also quite difficult to expand one of these later (other than just building another dome next to it and connecting them with a corridor), so it'd probably be much more plausible to build such structures as cuboids instead.
