This is a future where due to population pressure, the dry bits of the world have been built over with vast multi level cities. These constructions are made possible by the use of 'ice' as a building material. Ice is never explained as such but if you think of diamond fibre in a similar way to carbon fibre, I doubt you will go far wrong.
Each of the levels of the city represents a level in society, the physical following the metaphorical. Thus the cities are stratified in the same way as Han society has always been.
At the bottom, the first level above ground houses the great unwashed, the proles. Never stated explicitly, it is nonetheless apparent that Wingrove sees this level of hopeless people as necessary for the healthy functioning of the whole structure. Such concepts have been explored elsewhere. For instance 'Downbelow' on Babylon 5.
Spanning thirteen years, the book is very much written as a future history, (with more to come). It is told through the eyes of a larger number of characters than is normal for a book of this type. At first this is quite tedious, but as the story unfolded I found myself greeting the introduction of a new character perspective with some anticipation. The reason for this is that while initially the characterisations are almost cardboard cuttout, they grow through the eyes of the other observers. This necessarily takes some time to develop. Another quirk which I found excedingly anoying to start with is the use of Chinese phrases. Again this pays off in the end by enriching the culture that the book so succesfully portrays. I was left in no doubt that the language and behaviour of the Han characters and society had been painstakingly researched and extrapolated. What the book desperatly needs is a dramatis personnae, to get you through the first 150 pages or so. That it doesn't have one works to the books detriment. I can see how it would be easy to lay the book down 'to come back to', and then move on to easier reading. If as a result of this review you choose to read this book I urge you to stick with it until at least page 200. The perseverance is ultimately worthwhile as the story accelerates through ever increasing dramatic peaks to a satisfying conclusion. I will be hunting down the next book in the series, 'The Broken Wheel'.