Ormesson Castle, a historic estate in the same family since 1630, is gradually opening its doors to the public, especially during the Heritage Days and by appointment the rest of the year. Guided tours, around the park’s ponds and in the castle’s main reception rooms (whose decorations were completely restored in 2022, around furniture intact for more than a century), allow visitors to discover this high place of literary tradition which now holds the most important private archives of France. First attributed to Jacques and then to Baptiste Androuet du Cerceau, its construction dates from 1581 for Louis Picot de Santeny, Intendant of Finances of Henri III. The castle was enlarged when Louis XV decided to erect the land of Amboile-Ormesson as a Marquisate in 1758. Illustrious guests have honoured him with their visit, such as Bossuet, Madame de Sévigné, Diderot, the King of Württemberg, Queen Amélie of Portugal, King Mohamed V of Morocco, Princess Bibesco and Pope John XXIII. Olivier III d'Ormesson, Judge-Rapporteur at the Fouquet trial, Marshal Lyautey, and the latest Count Wladimir d'Ormesson, Ambassador of France to the Holy See...the greatest authors, parliamentarians, diplomats and academicians lived in these places. The park is made according to the drawings of Le Nôtre around a French perspective. A golf course completes the whole since 1925. In total, more than 140 hectares of greenery at the gates of Paris.