Château de Beauregard is a former house in La Celle-Saint-Cloud south-west suburbs of Paris, five kilometers north of Versailles. The name of the domain seems to have its roots in the Middle-Ages. The castle was built on a top of a hill between La Celle-Saint-Cloud and Le Chesnay. In the early XVIIe century, the house was owned by the du Val family, Pierre du Val was the House master of king of France. Then the castle was the property of the Montaigu family, which rented it. During the Revolution and Empire eras, ownership of the castle changed often.
In the mid 19th century, Harriet Howard bought the house and its park. She also bought the Béchevet farm and the Bel-Ébat stud farm, marking a very large 184 ha property. The castle was in a poor condition; she rebuilt in a neo-classical style. She also closed the whole area with a wall. From this castle, she worked for the success of Louis-Napoleon Bonaparte (later Napoleon III), of whom she was mistress and financial backer. She died in 1865.
Her son Martin-Constantin Haryett, created Earl of Béchevet by Napoléon III, was a spendthrift, and had to sell the castle in 1870 to the Duchess of Beauffremont. But a few months later, the Franco-Prussian War broke out. The Prussians, installed in La Celle Saint Cloud made Beauregard their headquarters, and built some fortifications. The Duchess of Beauffremont was ruined, was not able to rehabilite it, and the house was seized.