Grosbois Leave a Comment / Uncategorized / By admin From Paris Chatelet les Halles RER A to Boissy Saint Leger.In Boissy Saint Leger bus 21,23 or 451 direction Santeny, arrêt ‘Tournebride’. The castle of Grosbois is located in Boissy-Saint-Léger in the departement Val-de-Marne in the region of île de France. It is built in the 16th century by an unknown architect.