An artificial planet under construction, on the edge of a Dyson cloud. Done in Lightwave and Gimp.
For a scale reference, there are 16 thousand ships in the foreground, each the size of a modern freighter. The four metallic layers of the shellworld have the same transparency texture, 16000 by 16000 in cubic formation (that's right, cubic). Each pixel in this texture map would represent 750 metres. The same surfaces have a smaller texture (8000 by 8000) used for luminosity, mirror tiled every 1000 kilometres.
I was largely inspired by the SF art of the 70s and 80s, particularly the works that turned up in the Terran Trade Authority books.