BUR #17952 has been rejected.
create implication dyson_sphere -> megastructure
create implication floating_castle -> megastructure
create implication floating_city -> megastructure
create implication space_colony -> megastructure
create implication space_elevator -> megastructure
The tag megastructure is currently used as a catchall tag for any kind of absurdly large buildings and structures. Though thare are also a handful of megastructure types that get its own tag. To make the tag covers all type of megastructure, I think an implication is needed to link them together.
Note: I'm considered implicating Death Star from Star Wars as a megastructure, since it's literally an entirely artificial moon-sized weapon, though I would like to hear your comments whether if you wanted to consider it a megastructure or no.