If optimum stopped moving when they switched the generator off, then they're stuck on the shores of Portugal. The people from the city will never be able to go more than a few dozen miles from optimum without suffering increasingly severe hallucinations, possibly leading to insanity.

Downer Ending: The perception distortions caused by the translat generator are permanent.

Subverted, as the Atlantic Ocean is simply the first body of water flat-out impossible to drive around.

Contrived Coincidence: The fact that until the end of the novel, the city just happens to have been travelling over land for thousands of miles, never encountering a sea or major lake.Arranged Marriage: Helward and Victoria.Alien Geometries: Encountered far North and South.The story follows Helward as he tries to understand the nature of the strange inverted world in which he finds himself, and learns why the people of the City must forever struggle to keep moving it endlessly forward. Upon coming of age, Helward joins the Future Guild, allowing him to explore the world outside the City for the first time. Helward Mann is a citizen of the City of Earth, a massive rail-mounted structure which has somehow become Trapped in Another World. The Inverted World won an award from the British Science Fiction Association and was nominated for a Hugo. Originally published in 1974, it was republished in 2010 as part of the SF Masterworks Collection.

The Inverted World (also published as just Inverted World) is a science fiction novel by Christopher Priest, taking its concept (but none of its plot or characters) from a short story of the same name.

Christopher priest the inverted world