Alhóndiga y Pósito of Mexico City: a public grain exchange with a posted price, 1583

In 1583 the crown confirmed ordinances forcing every load of wheat, flour and barley entering Mexico City into one public hall, where the first price of the day stood all day, carriers had to produce a magistrate's certificate of what they had paid, and grain unsold in twenty days was sold by order. A levy on the same grain funded a granary that bought maize in scarcity and resold it below market. The granary was gone by 1830 and its levy paid for street lamps.