[1] The original castle was founded in the 11th century on the eastern border of Brittany and, such as the fortresses in Vitré, Fougères, Ancenis and Clisson, it was defending the duchy against Anjou and the Kingdom of France.

Eventually, during the 16th century, the château obtained its definitive appearance when the new Renaissance palace was built against the medieval enceinte.

After the French Revolution, the château was sold and divided several times, and was finally transformed into an administrative centre, with the seat of the sous-préfecture, a court and a police station.

To the north, it is bordered by the river Chère which forms a natural moat, and on the south by a wide square, the place Charles-de-Gaulle.

The Chère is retained by a medieval dam and forms a pond, the étang de la Torche.

The subsoil in Châteaubriant is made of sedimentary rocks (schist and sandstone) belonging to the Armorican massif.

[citation needed] It was first built by Brient, an envoy of the count of Rennes, to create an outpost in the Pays de la Mée.

This region around Châteaubriant was then a buffer zone between the counties of Rennes, Nantes and Angers, but also a place for trading.

Brient is also responsible for the construction of the Béré church and priory, two major landmarks of medieval Châteaubriant.

[6] In 1486, the baroness of Châteaubriant, Françoise de Dinan, the last of her family, opposed Francis II of Brittany.

She prepared the "Châteaubriant treaty" by which the barons of Brittany asked the King of France to settle a Breton internal dispute.

The treaty, which betrayed the authority of Francis II, was one of the reasons for the Mad War and showed the weakness of the Duchy of Brittany as a political entity.

The constable completed the works begun by Jean de Laval but established his residence at the Château d'Écouen, close to Paris.

The Condés slightly improved the château, for example in redesigning some rooms, such as the Chambre dorée in the Jean de Laval wing, decorated after 1632.

The distance of the Dukes of Montmorency and later the Princes of Condé permitted the town council to gain some independence, but the lords still maintained local officers in the château.

The town council, in need of buildings for its jail, court and services, wanted to buy the château, but the prince did not wish to deal with the administration, and the mayor bought the property personally.

He left the lower bailey gatehouse to the département, which transformed it into a jail, and sold the rest to the town council.

[11] The police station, the court and the jail, which were relocated somewhere else after the Duke of Aumale acquired the estate, came back in 1855.

[12][13] In 1887, the département asked for the removal of the château from the monument historique list because it could not afford the repairs required by the authorities.

[9] Nonetheless, the château has never been fully opened to visitors, who can only access the wards and some rooms, such as the Chambre dorée and the Bâtiment des Gardes which hosts exhibitions.

The small hall, partially destroyed, has a peculiar roof, similar to a flat onion dome, made around 1562.

At that time, French architecture had changed a lot: medieval features still in use at the beginning of the 16th century were totally rejected for Italian designs.

It is opened on the bailey by large windows bordered by tuff pilasters and small niches and it has Italian sculpted dormers.

On the external facade, the architect reemployed the medieval walls and towers and opened them with large windows and dormers.

Although very Italian in design, the building retained some French typical features, such as a steep slate roof and high chimneys.

Tuff, extremely common on the châteaux in the Loire Valley, because it is easily found there, had to be imported to Châteaubriant and was only used for ornamental purpose.

A monumental staircase was built at the junction between the Jean de Laval wing and the Bâtiment des Gardes.

[16] The great gallery was originally closing the garden in front of the Jean de Laval wing and it was connecting it to the keep.

After the death of Anne and her husband Louis XII of France, the new King, Francis I, asked Jean de Laval to come to his Court to help him settle the French annexation of Brittany.

According to some rumors, Jean de Laval would also have locked up his wife in a room, and later poisoned her or bled her to death.