In the Book on the Byzantine style, some of the examples in Jerusalem ascribed to Constantine have been transferred to Justinian’s time; but this has naturally followed another very important change—the description of the so-called Mosque of Omar, the Dome of the Rock, has been transferred to the Saracenic style. It is well known that Mr. Fergusson had few supporters in his theories respecting the builders of this structure, and Prof. Hayter Lewis’s work has now removed all doubt as to its having been the work of the Caliph Abd el Melik and his followers. This change has necessitated a complete revision of the description of the Holy Sepulchre, for which Prof. Willis’s and Prof. Hayter Lewis’s works have furnished the chief authorities. Various corrections have been made in the dates ascribed to the Mosques in Cairo, and the French Expedition in Tunis has enabled the editor to add a plan and view of the great Mosque of Kerouan, the most sacred Mahomedan edifice after that of Mecca, and the one great early example of which scarcely anything was known. About forty woodcuts have been specially prepared for this new edition, half of which are of subjects not before illustrated, the remainder replacing those which were defective or absolutely incorrect. In addition to these, various alterations where required have been made to other woodcuts. The several authorities consulted have been acknowledged in the course of the work, but the editor desires here to express his obligations to Mr. Fitzroy Doll, Mr. G. H. Birch, and Mr. Arthur Hill for advice on the German, English, and Irish sections respectively. PREFACE TO SECOND EDITION. During the period that has elapsed since the first edition of this work was published,[1] no important work on the History of Architecture has appeared which throws any new light on either the theory or practice of the art, and, except in India, no new buildings have been discovered and no monographs published that materially add to our general stores of knowledge. The truth of the matter appears to be that the architectural productions of all the countries mentioned in these two volumes have been examined and described to a sufficient extent for the purposes of the general historian. A great deal of course remains to be done before all the information required for the student of any particular style can be supplied, but nothing of any great importance probably remains to be discovered in the countries of the Old World, nor anything that is at all likely to alter any views or theories founded on what we at present know.