Château de Princé, Medieval castle ruins in Chaumes-en-Retz, France.

Château de Princé is a medieval castle in Chaumes-en-Retz where only foundations and partial stone walls remain standing today. These ruins reveal the basic layout of what was once a fortified residence with defensive structures.

The oldest castle on the site, a feudal stronghold ringed by moats, is documented in 1382, when Jeanne Chabot, called Jeanne la Folle, lady of Retz, lived there; in 1400 she gave the seigneurie of Princé to her grandson Guy de Laval. Henri de Gondi, former duke of Retz, died at the castle on 12 August 1659. In 1778 Jean Guillon, king's secretary, built a modern château and a quadrangular belvedere on the tower; republican troops under adjutant-general Jordy burned the castle on 2 December 1793 during the Vendée war.

The gardens of the Îles Enchantées were laid out around 1678 for Henri de Gondi, duc de Retz, on a plan by François de La Pointe. Five islands were enclosed by nearly a kilometre of canals, with a central square formed by two crossing rectangles, the east-west one measuring 130 by 78 metres. Villagers of Chéméré later held kermesses there, and a podium survives from that use.

The ruins stand on private land along the route de Vue at Chéméré, in Chaumes-en-Retz, and cannot be entered. The stone walls and the ivy-covered section are seen from the surrounding lanes and paths. The wooded setting of the former forêt de Princé and the canals of the Îles Enchantées lie nearby.

Gilles de Rais, born around 1405 and later infamous as Bluebeard, gave his name to a five-storey tower of the castle, the Tour de Barbe-Bleue. That tower collapsed and vanished in the early 20th century; only a small corner tower called "la chapelle" still stands on the site.