Ambrogio Lorenzetti, Effects of Good Government in the City, 1338–1339

Ambrogio Lorenzetti's fresco of the well-governed city, painted for the Sala dei Nove of the Palazzo Pubblico in Siena between 1338 and 1339. The right half of the wall is a street of trades: a shoemaker's shop, a cloth merchant behind a counter, panniered donkeys bringing goods in through the gate, a carter, a woman carrying a basket on her head.
Painted while the Champagne fairs were fading and the Sienese banking houses were at their height, this is the closest thing medieval Europe left to a portrait of its own commercial life. It is a picture of exchange rather than of a battle or a saint: goods on a counter, pack animals under load, a building site above the roofline.
public-domain — source (Wikimedia Commons (Google Art Project)). Free to reuse under the stated licence.