The Kaabah, or “square house,” built by Mahomet at Mecca upon the site of a temple which tradition says was founded by Abraham, appears to have been the earliest Mahometan mosque. Mahomet had already erected a building at Medina, but this seems to have been not so much a house of prayer as a dwelling-place for his family. The Kaabah has less importance as an architectural production than as the centre of the wheel of Mahometanism, the faithful being directed to turn their faces toward it when praying, and to regard it as the ultimate goal of their wanderings. The original structure was built by foreign workmen, and had no great pretensions, but subsequently it was surrounded by a colonnaded court, and by later additions was very considerably enlarged. Although the Koran decrees that all good Mussulmen should make a pilgrimage to Mecca, it does not uphold the Kaabah as a model to be followed in the erection of other mosques nor give any specific directions of the manner in which they should be built. It was therefore natural when the peace, following their rapid conquests, permitted the Mahometans to turn their thoughts to the erection of religious edifices, suitable for the observances of their worship, that they should borrow inspiration from the surrounding nations. The style they eventually evolved was drawn from Byzantine, Sassanian, Greek, and Roman sources, and became native by adaptation. In Turkey, Asia Minor, and Persia we find Mahometan mosques closely resembling Christian and Byzantine churches, many domed edifices being copied from St. Sophia and differing only in point of decoration, while the atrium or courtyard preceding the entrance to Christian buildings furnished the type for the wide colonnaded courts, with porticos roofed with a succession of hemispherical or bulbous domes, which became so common in Arabian buildings. The mosques of Omar, at Jerusalem, on the site of the temple of Solomon, of Wallid, at Damascus, Al-Azhar, Athar-en-Neby, Ibn Touloun, and Hassan, in Cairo, are notable edifices, in which the columns are either taken or copied from Greek and Roman temples, and in which the pointed arches seem to have been suggested by the hyperbolic arches of certain ancient Sassanian structures, such as the palace of Coroes, the Takt Kesra in the ruins of Ctesiphon, on the Tigris, and the buildings of Firouzabad and Sarbistan, which were mentioned in connection with Persian art. One of the earliest examples of the use of the pointed arch is in the Nilometer, erected on the Rodah, or Isle of Gardens, at Cairo, by Wallid, in the eighth century. This is a matter worthy of note, as showing conclusively that the Gothic arch was no invention of the thirteenth century, in Europe, but merely the adoption of a form used five centuries before in Egypt, and probably universally known, if indeed it had ever been lost sight of, since the days of the prosperity of Babylon.