Sebastiano Serlio was the most important architectural writer and theorist of the sixteenth century. The author of the first wide-ranging illustrated book on architecture, he produced a complete set of model designs as well as practical solutions for everyday design problems. This volume, the second in a two-volume series of Serlio's entire works, presents the previously unpublished sixth book, the seventh book, and, as well as The Extraordinary Book of Doors, his little-known Castrametation of the Romans, each of which demonstrates Serlio's sophisticated design theories. This is the first translation of Serlio's later works and the first time that the long lost sixth volume has been united with its companion works and restored to its intended position. The book also includes an introduction and notes by translators Vaughan Hart and Peter Hicks that demonstrate Serlio's significance within the history of architecture and the importance of these neglected texts to our understanding of Serlio's work.