Inverted World is a very scientifically-grounded dystopic novel (the afterword classifies Inverted World as a Hard SF novel but it doesn't seem that way at first; it seems more typical of a dystopic novel but about halfway through the Hard SF elements start poking their way through).
A walled city is being winched through a devastated landscape on rails. The rails must be laid before it and taken up after. The city is forever in chase of The Optimum. To halt is to fall victim to a crushing gravitational pull.
Helward Mann is our guide to this world. When he takes the oath to become a Future Surveyor, he is inducted to all the secrets normally kept from the city population. The dystopic novel was previous to this point, now it's Hard SF's turn.
History, geography, and physics all come into play. Is this world truly inverted, that only the enlightened of the city will follow the Optimum and avoid death, or are those in the city chasing a truly delusional vision?