8There are also circular temples, some of which are constructed in monopteral form, surrounded by columns but without a cella, while others are termed peripteral. Those that are without a cella have a raised platform and a flight of steps leading to it, one third of the diameter of the temple. The columns upon the stylobates are constructed of a height equivalent to the diameter taken between the outer edges of the stylobate walls, and of a thickness equivalent to one tenth of their height including the capitals and bases. The architrave has the height of one half of the thickness of a column. The frieze and the other parts placed above it are such as I have described in the third book, on the subject of symmetrical proportions.
2But if such a temple is to be constructed in peripteral form, let two steps and then the stylobate be constructed below. Next, let the cella wall be set up, recessed within the stylobate about one fifth of the breadth thereof, and let a place for folding doors be left in the middle to afford entrance. This cella, excluding its walls and the passage round the outside, should have a diameter equivalent to the height of a column above the stylobate. Let the columns round the cella be arranged in the symmetrical proportions just given.
3The proportions of the roof in the centre should be such that the height of the rotunda, excluding the finial, is equivalent to one half the diameter of the whole work. The finial, excluding its pyramidal base, should have the dimensions of the capital of a column. All the rest must be built in the symmetrical proportions described above.
4There are also other kinds of temples, constructed in the same symmetrical proportions and yet with a different kind of plan: for example, the temple of Castor in the district of the Circus Flaminius, that of Vejovis between the two groves, and still more ingeniously the temple of Diana in her sacred grove, with columns added on the right and left at the flanks of the pronaos. Temples of this kind, like that of Castor in the Circus, were first built in Athens on the Acropolis, and in Attica at Sunium to Pallas Minerva. The proportions of them are not different, but the same as usual. For the length of their cellae is twice the width, as in other temples; but all that we regularly find in the fronts of others is in these transferred to the sides.
5Some take the arrangement of columns belonging to the Tuscan order and apply it to buildings in the Corinthian and Ionic styles, and where there are projecting antae in the pronaos, set up two columns in a line with each of the cella walls, thus making a combination of the principles of Tuscan and Greek buildings.
6Others actually remove the temple walls, transferring them to the intercolumniations, and thus, by dispensing with the space needed for a pteroma, greatly increase the extent of the cella. So, while leaving all the rest in the same symmetrical proportions, they appear to have produced a new kind of plan with the new name “pseudoperipteral.” These kinds, however, vary according to the requirements of the sacrifices. For we must not build temples according to the same rules to all gods alike, since the performance of the sacred rites varies with the various gods.
7I have now set forth, as they have come down to me, all the principles governing the building of temples, have marked out under separate heads their arrangements and proportions, and have set forth, so far as I could express them in writing, the differences in their plans and the distinctions which make them unlike one another. Next, with regard to the altars of the immortal gods, I shall state how they may be constructed so as to conform to the rules governing sacrifices.