The world of Sun of Suns written and created by Karl Schroeder is a complicated one and while it explains lots of things, it also leaves plenty to the imagination. It is not, however, a ringworld or halo construct. Think more on the lines of Niven's Integral Trees environment.
- While the environment is quite sophisticated and indicates a very advanced society, the current citizens of the world are not the makers of this environment. Their technology is pre-computer, advanced mechanical with a few outlying technologies. I hesitate to say steampunk due to the advanced nature of the setting but it has been used to describe the tech level. Movement is done using small jet propelled aircraft, presumably clean burning and highly efficient. People have also been known to travel by airship or by flying personally with winged (unpowered) exosuits.
The environment Virga is essentially a fullerene gas bag around a star (possibly an artificial one in the center of the gas bag. The bag is two meters thick, rigid and encased in an icy glacier. There are asteroids and bodies of water floating inside of this gas bag in slow orbits around the tiny interior sun. The bag is filled with water vapor which keeps the temperature regulated and allows people to exist without freezing until they move away from the main sun.
The entire Virga region is listed at 5000 miles across and at in the center of this fullerene sphere is an artificial sun which provides a central mass for objects which float in Virga to orbit, very slowly. However, this sun does not provide much light and apparently not much heat either, because citizens of this world who choose not to live near that sun have pushed off and found other floating debris, large rocks and the like and anchor themselves to those rocks and create their own smaller suns for lighting and heat. (This is frowned upon but apparently not easy to stop.)
- Move far away enough from the main sun and you reach an area of the Virga called Winter, where it is too cold to exist without an artificial sun. Resources also seem to be a bit scarce so fewer people choose to live out there, or it is simply harder to get by. On the diorama below, it shows suns and large land masses, with the giant diamond, I assume is the central sun/mass with the smaller jewels being land masses and artificial constructions.
- The living areas vary in size from little more than towns which are rope and wooden constructions built on the inside of a wheel (imagine a bicycle wheel made of rope and wood and the people live in houses on the inside of the wheel). Cities grow in size when they can tether themselves to large asteroids and using fans and sails maintain their position around their drifting land mass. This image also shows geared cylinders connected to each other in the far right corner.
More complicated cities become cylinders made of metal (presumably mined from the floating asteroids). There can be multiple cylinders connected together in multiple arrangements, and since there is no gravity, once you move away from the centrifugal gravity, you are able to float/fly between rings, or cylinders.
There are potentially hundreds of townlets/cities depending on population, availability of resources and military capability. The town shown below was considered to be a town not wealthy enough to have its own sun. You can use it as a marker for scale.
All of these images are from Karl Schroeder's comic representation of his work at http://virgacomic.com/ where he and a talented group of writers, scripters and artists convert his vision into a comic format. His site also gives you a map and a description of how his world works.