Brunelleschi, Alberti, Michelangelo, and Palladio taught themselves how to become architects by studying ancient buildings and Vitruvius, and they replaced Medieval styles with a new design tradition. In this volume, the writings of Alberti, Palladio, and Vasari are compared to determine how buildings were designed and constructed during the Italian Renaissance. Michelangelo's drawings, letters, models, and other primary sources have been reconsidered to reconstruct how he intended for St. Peter's Basilica to look. My conclusion is that he planned to add a six-columned portico and to have a dome of similar height to the present dome, but which was also to have had a lower U-shaped dome on the interior. The work of other architects is also reconsidered mainly on the basis of primary sources.Appended are discussions of the recovery of ancient knowledge during the Renaissance and the role of Aldus Manutius in printing Greek and Latin classics. The Renaissance became increasingly secular in education as well as in architecture and art until the Counter-Reformation reimposed censorship.