Arnouville: this unfinished château in the Val-d'Oise opens its doors

Seven years of construction, an aisle completed with a chapel, a meticulously designed French garden: the Château d'Arnouville, in the Val-d'Oise, boasts all the hallmarks of an 18th-century grand residence. Except it was never finished. Built between 1751 and 1757 for Jean-Baptiste de Machault d'Arnouville, Controller-General of Finances and later Keeper of the Seals under Louis XV, the estate now houses a therapeutic institute for children. On Sunday, 20 September 2026, two guided tour slots will allow visitors to discover the château and its park.