The raising of a dome upon a drum or tower is common both in the East and West. In many instances, and especially in Mahometan buildings, the dome becomes an important external feature. The crowning of the dome by a small tower or lantern on its apex is frequent among the early domes of Northern Italy, and is seen on the five domes of St. Front at Perigueux, and, in a different form, on its prototype at Venice. The internal range of windows beneath the dome is found both in the true Byzantine districts, in Italy, in France, and in Germany; and finally, the independence of the external and the internal domes,--the former becoming the roof to the latter, with even the intermediate structure to support the culminating turret or lantern,--is found in its full integrity in St. Mark’s, at Venice, where its early date is proved by its being represented in the most ancient of the external mosaics. Why, then, if all its essential characteristics are to be found in ancient examples, do we call this form of dome “_modern_”? I would reply that, though its elementary ideas were old, their systematic combination, and the vast scale on which they were worked out, is due to the architects of the Renaissance. It is, in my opinion, their greatest achievement, being the union of the Classic with the Byzantine and the Mediæval ideals, and the working them into a feature which no previous style had produced in so complete a manner or on so noble a scale. In saying this, however, I do not intend to praise this as being as an internal feature superior to the true Byzantine dome; on the contrary, I think it a less reasonable and an even less beautiful covering, because it is raised to so vast an elevation as not to be visible at any natural angle of vision, nor to become a part of the general internal view of the building. It must, however, be confessed that, _when seen_, it is of wonderful and almost magical aspect; while externally it produces a nobler form of tower than is to be found in any previous development. I do not think it in any degree belongs essentially to the Renaissance, though it chanced to be developed under its influence. On the contrary, the first complete type of this form of dome (though happening not to be pendentive) was designed as the completion of a Gothic structure, and its only serious fault is that it was not carried out with more perfectly Gothic detail. I refer of course to that of the Cathedral at Florence (Fig. 451). [Illustration: Fig. 451.--Cathedral at Florence.]