Between 1942 and 1943 seventeen important Italian architects published in “Domus”, which is one of the most prestigious journals of architecture, the designs of their ideal houses. The analysis of their proposals is singularly instructive for those philosophers who are interested in reasoning on the notion of ideal: the results of a precise concrete use of it clarify its philosophical meaning both in regard with the notion of ideal in general and in regard with the notion of ideal human being in particular, if it is true that these architects’ exercises of imagination prove that there is no thought of ideal house if there is no thought of ideal human being as its foundation.