Tower of Cesson, Fortified tower in Saint-Brieuc, France

The Tower of Cesson is a ruined stone tower on a rocky spur above the Gouët estuary and the bay of Saint-Brieuc. Its walls of rough light-brown and gray masonry rise to a broken, uneven top. The front face has a large arched window upper left, a smaller rectangular hole below it, and a smaller arched opening to the right; three stacked small arched recesses sit higher on the right, and a vertical channel of missing stone runs down the left side.

Jean IV of Montfort, Duke of Brittany, ordered the tower built from 1395, and work continued under his successor Jean V. It stood about 70 m high on a rocky spur above the Gouët estuary to guard Saint-Brieuc from pirates and to watch maritime trade. In 1598 the Comte de Brissac took it and had the fortress dismantled; part was kept from 1625 as a landmark for sailors.

The tower's name survives in Breton as Tour Saozon. After the Wars of the League it was partly kept from 1625 to serve as a landmark for sailors entering the Gouët estuary. The site later passed to the duc de Penthièvre and was sold in 1791.

The tower stands on private land that had long been abandoned; the city of Saint-Brieuc has owned the site since November 2020 and plans to open it to the public. The adjacent manor, built by the Glais-Bizoin family, was damaged by arson on 25 January 2018. The base of the tower is screened by bare trees, so the masonry is best seen from a distance.

After the 1598 siege, the comte de Brissac had the fortress dismantled at the inhabitants' request, but one part was kept from 1625 to serve as a landmark for sailors entering the bay. The ruined tower still stands on the private Cesson estate, which the city of Saint-Brieuc acquired in November 2020.