Artificial worlds or artificial planets have been created by writers in the fields of science speculation, speculative fiction and fiction. Such megastructures could have a variety of advantages over natural planets, such as efficient use of solar energy and immense living space, but their construction and/or maintenance would require technologies so much more advanced than those of 21st-century Earth that it is currently unknown if they are even achievable. Examples of artificial worlds include: * Culture Orbitals * Dyson spheres * Globus Cassus * Ringworld