Why it looks like this

Datong was a garrison city guarding China's northern frontier: its Ming walls, first raised in the 14th century, enclosed a square grid of streets crossed at the centre by drum and bell towers. In the 20th century it became one of China's great coal capitals, and the mines and railways drew a sooty industrial city around the old town.

In the 2000s the mayor rebuilt the entire circuit of walls and much of the 'ancient' city inside them, relocating tens of thousands of residents — one of the largest and most debated heritage reconstructions ever attempted. The crisp square on today's map is partly a modern copy of its own past.