The at the end there is a Big Reveal, which completely inverts our take on the city and what exactly is going on. I see some critics complaining that this spoils the story, but for me it doesn't - it makes the point that everyone's perspective is wrong, in the end, and the inversion may not be where you think. Having said that, the logic of the conclusion is not a hopeful one for the people of the city.
By the way, this is one of the longest great circles on land, Hong Kong to Lisbon:
I have spent some fruitless time trying to identify a credible longer route from south-eastern China to Sierra Leone or Liberia, skirting north of the Gulf of Suez and south of the Caspian, but am not convinced by any of the options. If there is one, it would be significantly longer than the Portuguese option.