This article traces the increasing theorization of secret spaces tailored for the prince's household in 15th- and 16th-century architectural treatises. From Leon Battista Alberti to Francesco di Giorgio Martini, architects and humanists conceived of the prince's household as one in which secret and public spaces were carefully distinguished. A number of architectural devices, such as secret doors, private stairs and listening tubes were designed so that the prince could be able to control all movements in his household. The echoes of this theorization, mediated by later treatises, such as that by Sebastiano Serlio, can be traced in 16th- and 17th-century literary works, such as those by Bartolomé Torres Naharro or Lope de Vega, both in the Italian and the Iberian Peninsula. [ABSTRACT FROM AUTHOR]