Few revolutions more sudden, more signal, and more widespread are recorded in history than that which covered not only the East but part of the West with the Mohammedan religion and dominion. Mohammed was born either in the year 569 or 570 of the Christian era, and died A.D. 652. The year of the Hegira, the era from which Mohammedans compute their chronology, is A.D. 622, and within little more than a century from this era the Prophet was acknowledged, and the suzerainty of the Caliph recognised eastwards, in Arabia, Syria, Palestine, Egypt, and Persia, and in India as far as to the Ganges; and westwards along the north coast of Africa, in Sicily, and in Spain. It was only to be expected that such a wonderful tide of conquest and such a widespread change of religion should before long leave its impress on the architecture of the continents thus revolutionised; and accordingly a Mohammedan style soon rose. This style did not displace or override the indigenous art of the various countries where it prevailed, as Roman architecture did in the age of universal dominion under the Empire; it assimilated the peculiarities of each country, and so transmuted them, that although wherever the religion of Mohammed prevails the architecture will at a glance confess the fact, still the local or national peculiarities of each country remain prominent. The Arabs, a nomadic race who lived in tents, do not seem to have been great builders even in their cities. We have no authentic accounts or existing remains of very early buildings even in Mecca or Medina, as the oldest mosques in those cities have been completely rebuilt. It is to Egypt and Syria that we must turn for the most ancient remaining examples of Saracenic architecture. These consist of mosques and tombs. _Egypt._ A mosque--or Mohammedan place of worship--has two forms. The earlier mosques are all of them of a type the arrangement of which is simplicity itself. A large open courtyard, resembling the garth of a cloister, with a fountain in it, is surrounded cloister-wise by arcades supporting timber roofs. On the side nearest Mecca the arcades are increased to several rows in depth, so as to cover a considerable space. This is the part in which the congregation chiefly assembles; here a niche or recess (termed Kibla), more or less enriched, is formed in which the Koran is to be kept, and hard by a pulpit is erected. For many centuries past, though not, it is believed, from the very earliest times, a minaret or high tower, from the top of which the call to prayer is given, has also been an indispensable adjunct to a mosque.