The 16th-century art historian Giorgio Vasari proposed that Brunelleschi was the palazzo's architect, and that his pupil Luca Fancelli was merely his assistant in the task but today it is Fancelli that is generally credited.[3] Besides obvious differences from the elder architect's style, Brunelleschi died 12 years before construction of the palazzo began. The design and fenestration suggest that the unknown architect was more experienced in utilitarian domestic architecture than in the humanist rules defined by Alberti in his book De Re Aedificatoria.