It has often been observed that a building, in order to show its magnitude, must be seen all at once. It would, perhaps, be better to say, must be bounded as much as possible by continuous lines, and that its extreme points should be seen all at once; or we may state, in simpler terms still, that it must have one visible bounding line from top to bottom, and from end to end. This bounding line from top to bottom may either be inclined inwards, and the mass, therefore, pyramidical; or vertical, and the mass form one grand cliff; or inclined outwards, as in the advancing fronts of old houses, and, in a sort, in the Greek temple, and in all buildings with heavy cornices or heads. Now, in all these cases, if the bounding line be violently broken; if the cornice project, or the upper portion of the pyramid recede, too violently, majesty will be lost; not because the building cannot be seen all at once,--for in the case of a heavy cornice no part of it is necessarily concealed--but because the continuity of its terminal line is broken, and the _length of that line_, therefore, cannot be estimated. But the error is, of course, more fatal when much of the building is also concealed; as in the well-known case of the recession of the dome of St. Peter's, and, from the greater number of points of view, in churches whose highest portions, whether dome or tower, are over their cross. Thus there is only one point from which the size of the Cathedral of Florence is felt; and that is from the corner of the Via de' Balestrieri, opposite the south-east angle, where it happens that the dome is seen rising instantly above the apse and transepts. In all cases in which the tower is over the cross, the grandeur and height of the tower itself are lost, because there is but one line down which the eye can trace the whole height, and that is in the inner angle of the cross, not easily discerned. Hence, while, in symmetry and feeling, such designs may often have pre-eminence, yet, where the height of the tower itself is to be made apparent, it must be at the west end, or better still, detached as a campanile. Imagine the loss to the Lombard churches if their campaniles were carried only to their present height over their crosses; or to the Cathedral of Rouen, if the Tour de Beurre were made central, in the place of its present debased spire!