Who
Who was Etienne?
Etienne (Nasr'Eddine) Dinet was a French painter of the Orientalist school who lived in the in the late 1800s and early 1900s. The Chateau d'Héricy was both his boyhood and adult residence; he used this tower on the corner of the property as his artists' studio. It now houses a library and can be used as an office or studio.
A biography of Dinet can be found here.
Etienne Dinet, Self Portrait