A farmer sketched a model city ringed by farmland, and the model still holds up

In 1826, Prussian farmer and economist Johann Heinrich von Thünen imagined an isolated city on a flat, featureless plain, and worked out what farmers around it would grow, based purely on transport cost. His model predicted concentric rings: perishable dairy closest in, then firewood, then grain, with livestock pushed furthest out since animals can walk themselves to market. It became one of the first mathematical models in economics and still shapes how geographers explain land use.

— Johann Heinrich von Thünen, Der isolierte Staat (The Isolated State) — 1826