A true planned unit development, a bastide began as a contract of paréage between the king and a local seigneur that defined its configuration, population, and economic protections. Peasants were offered their own plot of land, exempted from military service, guaranteed protection and given the right to inherit. In exchange, they had to come, settle, build, and defend the town.
Bastides were laid out, using professional surveyors, on a pure rectilinear plan with alternating wide (26 feet) streets and narrow alleys that cut the bastide's quarter-mile area into equal squares - essentially the same principles used by the Romans in their new towns (or, even further back, at Pompeii and Herculaneum). Usually a pre-existing defensive structure like a chateau or a fortified church would form part of the walls. Inside, the bastide was organized around a covered market in an open square at the bastide's center. Covered walkways called couverts gave access onto the market square and held storefront shops.
Major bastide sponsors were the counts and seneschals of Toulouse, Alphonse de Poitiers (1249-71) and Eustache de Beaumarchais (1272-94) and, for the English, Edward I Plantagenet (Longshanks, the Hammer of the Scots, William Wallace's conqueror from Braveheart).