The Walls and Roof of this Church are built with Brick. The Inside of the Walls of the Church are incrusted with elegant Marble of several Kinds. All its Materials are the most valuable Productions of Nature, so that the Prospect of it employs the Thoughts of the Spectator with Delight and Admiration. The Roof of it is a surprizing Piece of gilded _Mosaick_ Work, which reflects such a Lustre upon the Eye, that even the _Barbarians_ who behold it, are wonderfully taken with the Sight of it. This Roof is supported with eight Pillars, four of the largest and tallest of which bear up the four Arches which support the Roof. Two of these Arches, _viz._ the Northern and Southern, bear at the Bottom of their Curvature upon a thin Wall full of Windows, which Wall is strengthen’d by two Ranges of Pillars standing one above another. In the lower Range stand eight Pillars, which rise from the Pavement, the six above them support the thin Wall. The Eastern and Western Arches have neither a Wall nor a Pillar to support them, but are so open, that they make the Body of the Church appear more large. For these Arches projecting beyond the former, bear upon four other Arches, which are supported by two small and two large Pillars: For the four large Pillars do not only bear up the four great Arches, but every one of them does also support two small Arches, one of which extends itself length-ways, the other cross-ways of the Church; by which means the Church is lengthen’d and widen’d to a great Distance; for on the East and West Side of it there are two _Semi-domes_ which are join’d to the _Cupola_ in such a Manner, that they have the same Roof within the Church, though without it the Roofs seem to be distinct. These _Semi-domes_ are a great Ornament to the _Cupola_, which rises very highly above them. The Breadth of the Church is widen’d beyond the _Dome_ with Arches and Pillars, and the Northern and Southern Wall, which form the three upper and three lower Galleries, which are incrusted with elegant Marble of different Kinds, the Roof of them being cover’d with _Moresco Mosaick_ Work, finely gilded. Every Arch which lies across the Church bears only upon one Pillar, for one End of their Curvatures is supported by the outward Wall of the Church, which bears upon large Pillars, from whence there rise four Arches, which on both Sides of the Church are supported by the Wall. Two of these Arches bear up the Roof of the three lower Galleries, and the other two support the Roof of the three upper Galleries, the Sides of which bear upon Walls, and Arches, and Pillars. Hence it is, that if we consider the Inside of the Church by itself, as enclosed by its Pillars and Columns, we discover it to be of an oval Figure; whereas if we view the whole Space of it without these Pillars, it is a perfect Square. For the upper and the lower Galleries, which are the Wings of the Church, adjoin to it in such a Manner, that if we measure it from