I must begin by saying that according to this model, made under the direction of Michelagnolo, I find that in the great work the whole space within the tribune will be one hundred and eighty-six palms, speaking of its width from wall to wall above the great cornice of travertine that curves in a round in the interior, resting on the four great double piers that rise from the ground with their capitals carved in the Corinthian Order, accompanied by their architrave, frieze, and cornice, likewise of travertine; which great cornice, curving right round over the great niches, rests supported upon the four great arches of the three niches and of the entrance, which form the cross of the building. Then there begins to spring the first part of the tribune, the rise of which commences in a basement of travertine with a platform six palms broad, where one can walk; and this basement curves in a round in the manner of a well, and its thickness is thirty-three palms and eleven inches, the height to the cornice eleven palms and ten inches, the cornice over it about eight palms, and its projection six and a half palms. Into this basement you enter, in order to ascend the tribune, by four entrances that are over the arches of the niches, and the thickness of the basement is divided into three parts; that on the inner side is fifteen palms, that on the outer side is eleven palms, and that in the centre is seven palms and eleven inches, which make up the thickness of thirty-three palms and eleven inches. The space in the centre is hollow and serves as a passage, which is two squares in height and curves in a continuous round, with a barrel-shaped vault; and in line with the four entrances are eight doors, each of which rises in four steps, one of them leading to the level platform of the cornice of the first basement, six palms and a half in breadth, and another leading to the inner cornice that curves round the tribune, eight palms and three-quarters broad, on which platforms, by each door, you can walk conveniently both within and without the edifice, and from one entrance to another in a curve of two hundred and one palms, so that, the sections being four, the whole circuit comes to be eight hundred and four palms. We now have to ascend from the level of this basement, upon which rest the columns and pilasters, and which forms the frieze of the windows within all the way round, being fourteen palms and one inch in height, and around it, on the outer side, there is at the foot a short order of cornice-work, and so also at the top, which does not project more than ten inches, and all of travertine; and so in the thickness of the third part, above that on the inner side, which we have described as fifteen palms thick, there is made in every quarter-section a staircase, one half of which ascends in one direction and the second half in another, the width being four palms and a quarter; and this staircase leads to the level of the columns. Above this level there