Ringworld

"Ringworld" is a science fiction novel by Larry Niven that features an enormous, artificial structure shaped like a giant ring encircling a star. This ring is a million miles wide, providing a vast habitable surface with Earth-like conditions, thanks to advanced engineering. The interior of the ring is a continuous landmass with rivers, cities, and ecosystems. The concept explores advanced technology and space habitats, offering a perspective on how future civilizations might live on megastructures that harness stellar energy and offer immense living space beyond traditional planets.