This book is devoted to three churches in ancient Ravenna that were built during the reign of the Emperor Justinian in the decisive period of his andiminstration and, at least in part, at his command.  Otto von Simson emphasizes the complex political, religious, and liturgical themes of the mosaics in these sanctuaries, providing important insights into the Byzantine society of the 6th c.  This edition includes forty-eight pages of improved illustrations.