The wind that built a city

Why are so many old cities on the eastern side of their rivers, or the northern side of their hills? The answer is often the wind, and the reason is less romantic than it sounds.

Before sewers and chimneys, a town produced smoke, animal waste and the smell of tanning and butchery. The prevailing wind carried all of it in one direction. Wealthier residents, who had a choice, settled upwind. Poorer residents lived downwind, because that land was cheaper, and it was cheaper precisely because of what arrived on the wind.

In western Europe the prevailing wind comes from the south-west. The pattern is visible on a map today: in London, Paris and many smaller cities, the historically wealthier districts sit to the west, the industrial and poorer districts to the east. The factories are gone, the smoke is gone, and the price difference remains.

This is a general pattern worth recognising. A reason disappears and the arrangement it produced stays, because housing stock, schools and reputations change far more slowly than the cause that shaped them. A visitor today sees expensive west and cheap east and may invent an explanation about character or fashion.

The real explanation is a wind that stopped mattering two centuries ago and is still being paid for in rent.