Years ago, on a board far, far away
, I played with a ringworld at the opposite end of the scale from Niven's Ringworld. It was a really thin band which is more-or-less of similar construction at any cross-section along its circumference. Hence the title. "Up" is towards the star, just like the Ringworld.
The occupied core is no more than 3km wide, with wider secondary rims for solar energy collection. A cross-section of the core ('left' to 'right') consists of: a canal; an accommodation and leisure belt; a central roadway/plaza; an industrial and hydroponics belt; and a mag-lev transport system in vacuum. The layout was inspired by Paul di Filippo's story A Year in the Linear City
The canal, accommodation, leisure belt, and roadway are roofed with a transparent material. There is no inner shadow-square ring to provide a day/night cycle, as the environment is sealed and pressurised and sections can be darkened individually. Underneath the floor of the ring lie the life-support and services tunnels. All the usual space station devices are employed, such as docking points for ships on the underside, internal compartmentalisation, etc.
The intention was to have this artefact orbiting a dwarf star of some sort, feel free to weigh in with your superior astronomical knowledge here.
Gravity is supposed to be spin-imparted, and there isn't supposed to be any gravitic tech here.