The merchant houses stand in a line along the river. Iwamatsu grew beside the Iwamatsu River, and its shops and storehouses follow the water rather than a surveyed street — so the road and the row of buildings both curve gently, taking the shape the river gave them. There is no grid here and there never was one; the town was laid out by the current.

A ryokan building that appears in a well-known novel still stands on the street, and the name of the town has travelled a good deal further than the town itself has, carried by that book. Uwajima's centre is about twenty-five minutes away by car. Citrus and fishing are the main occupations here, and the climate is mild even in winter, which is what makes the fruit possible in the first place. Because the river and the sea are both close, the oranges from the hills and the catch from the water arrived in the same town, on the same day, to be handled by the same merchants.

A zaigōmachi comes into being wherever goods converge from the surrounding country. Iwamatsu was positioned to receive both what the mountains produced and what the sea produced, so it functioned as a second centre for this district, separate from the castle town at Uwajima and answering to a different logic. The merchant houses line the river because what was collected here left by boat. The town is arranged along its outward route rather than around a square or a crossing, which is the characteristic layout of a place that gathered goods rather than producing them. Everything faces the way the cargo went.