This book owes much to many: to the Trustees of the American Academy in Rome, the John Simon Guggenheim Memorial Foundation, and the Research Committee of the University of Wisconsin Graduate School, for giving me the opportunity to spend three years in Italy; to Laurance and Isabel Roberts, for hospitality and moral support; to Axel BoËthius, for friendship and instruction; to Ernest Nash, for photographs and advice; to Mrs. Inez Longobardi, the best and most helpful of librarians and friends; to Ferdinando Castagnoli, for sharing with me his incomparable knowledge of the topography of Rome and Latium; to R.I.W. Westgate and Alston Chase, who taught me Latin at Harvard and have been my friends for thirty years; to the staff of the St. Martin’s Press: Diane Wheeler-Nicholson, and Fred J. Royar, for giving the book so handsome a dress; especially to my colleague J.P. Heironimus, for meticulous proofreading which saved me from much error; and to Frank E. Brown, who introduced me to archaeology and is hereby absolved from responsibility for all untoward results of the introduction. My overarching debt is acknowledged in the dedication.