Dinan, a town of Brittany, France, in the department of C6tes-du-Nord, on the Rance, 30 m. N. W. of Rennes; pop. in 1866, 8,510. It occupies a commanding and romantic site on the crown and slopes of a steep hill overlooking the narrow valley of the Rance, which flows 250 ft. below its summit. It is surrounded by a high wall, pierced by four gates, which anciently had 54 round towers, but has now but 16. The old and picturesque castle, built about 1300, is now a prison. On the outside of the walls, now overgrown with ivy, are beautiful terraces and gardens in the former moat. There are some fine specimens both of ancient and modern architecture. In one of the four open places is a statue of Du Guesclin, who successfully defended the town against the English in 1359. Its port can admit vessels of 90 tons burthen, and it has a considerable coasting trade. Its manufactures consist chiefly of linen, cotton, and- woollen goods, leather, beet-root sugar, and salt. In the environs are chalybeate springs, much resorted to.
It was often besieged in the middle ages.