The Chateau de Rosny-sur-Seine is a chateau in the Louis XIII style, situated in Rosny-sur-Seine in Yvelines, on the left bank of the Seine, at a short driving distance from Paris by the road to Rouen. It is famous as the seat of Maximilien de Bethune, duc de Sully, who retired to the old chateau to heal from his wounds at the battle of Ivry, 1590, and constructed the present building on old foundations in the closing years of the 16th century.
It went through several substantial alterations in the 19th and 20th centuries, and a period of neglect in the 1980s and 1990s. As of 2004, it is under renovation. The chateau was built of bricks and limestone by Maximilien de Bethune, duke of Sully, on the site of an old fortified manor that had been dismantled and burned in 1435.
The old building was inherited in 1529 by Jean de Bethune, the grandfather of Sully, who was born at the old house, but it was modest by the standards of the day, and he had it replaced in the last years of the 16th century with a new building more befitting his high rank. He is reputed to have ceased building in 1610 at the death of Henri IV, who had visited him there and whose monogram appears on the decorated joists of a room there.