Guillaume's son, Amaury began building a castle that would eventually become the eponymous Montfort-l'Amaury. The project, however, was incomplete when he died , but his son, Simon, finished it in 1067.
Amaury, Guillaume's son, initiated the construction of a castle which later became known as Montfort-l'Amaury. Unfortunately, the project was unfinished at Amaury's death, but his son, Simon, finished it in 1067.