The main entrance is to the west. This front is the latest portion of the building with the exception of certain portions of the interior. Though not as corrupt as some of the surgical decorations in the trascoro, it is the heaviest and least interesting part of the church. It bears no relation to the sides of the building, but seems to have been clapped on like a mask. The central portion is subdivided into three huge bays, the spring of the arch, which rises from the intermediate piers, being considerably higher in the centre than those of the two to the north and south. Diego de Siloé probably designed the composition, intending that it should be flanked and terminated by great towers. Three stages, rising to a height of some 185 feet, stand to the north. Corinthian and Ionic orders superimpose a Doric entablature over a plain and restrained base. Arches frame more or less meaningless and unpierced designs between the pilasters and engaged columns of the orders. The whole is as painfully dry as the transfer of a student's compass from a page of Vignola. Old cuts and descriptions represent this northern tower crowned by an octagonal termination with a height of 265 feet. Despite the apparent massiveness of the substructure, this soon made the whole so alarmingly insecure that it was pulled down. The present tower scarcely reaches above the broken lines and flat surfaces of the roof tiles and, particularly at a distance, has the effect of a huge buttress. The southern tower was never erected, but in place of it the front was supported by a makeshift portion of base. The northern tower is the work of Maeda, the façade principally by Cano, although much of the sculpture, such as the Incarnation over the central doorway, and the Annunciation and Assumption over the side portals, are by other inferior eighteenth-century sculptors. Statues, cartouches and ornamental medallions relieve the paneled surfaces of the stonework, the masonry of which has been laid and jointed with the utmost conceivable mechanical skill. The whole central composition fizzles out in a meaningless mass of parapets and variously carved stone terminations. One feels as if the original designer had started on such a gigantic scale that he either had to give up finishing his work proportionately or keep on till it reached the sky,--he wisely chose the former alternative.