Another building, which is now known as the Lateran Baptistery (Woodcut No. [422]), was also undoubtedly a place of sepulture. Its erection is generally ascribed to Constantine, and it is said was intended by him to be the place of his own sepulture. Whether this is correct or not, it certainly belongs to his age, and exhibits all the characteristics of the architecture of his time. Here the central apartment, never having been designed to support a dome, is of a far lighter construction, an upper order of pillars being placed on the lower, with merely a slight architrave and frieze running between the two orders, the external walls being slight in construction and octagonal in plan.[[188]] We must not in this place pursue any further the subject of the transition of style, as we have already trespassed within the pale of Christian architecture and passed beyond the limits of Heathen art. So gradual, however, was the change, and so long in preparation, that it is impossible to draw the line exactly where the separation actually took place between the two.
Temple of Minerva Medica.
One important building remains to be mentioned before leaving this part of the subject. It commonly goes by the name of the Temple of Minerva Medica, though this is certainly a misnomer.[[189]] Recently it has become the fashion to assume that it was the hall of some bath; no building of that class, however, was known to exist in the neighbourhood, and it is extremely improbable that any should be found outside the Servian walls in this direction; moreover, it is wanting in all the necessary accompaniments of such an establishment.
It is here placed with the tombs, because its site is one that would justify its being so classed, and its form being just such as would be applicable to that purpose and to no other. It is not by any means certain, however, that it is a tomb, though there does not seem to be any more probable supposition. It certainly belongs to the last days of the Roman Empire, if indeed it be not a Christian building, which I am very much inclined to believe it is, for, on comparing it with the Baptistery of Constantine and the tomb of Sta. Costanza, it shows a considerable advance in construction on both these buildings, and a greater similarity to San Vitale at Ravenna, and other buildings of Justinian’s time, than to anything else now found in Rome.
As will be seen from the plan and section (Woodcuts Nos. [228] and [229]), it has a dome, 80 ft. in diameter, resting on a decagon of singularly light and elegant construction. Nine of the compartments contain niches which give great room on the floor, as well as great variety and lightness to the general design. Above this is a clerestory of ten well-proportioned windows, which give light to the building, perhaps not in so effective a manner as the one eye of the Pantheon, though by a far more convenient arrangement, to protect from the elements a people who did not possess glass. So far as I know, all the domed buildings erected by the Romans up to the time of Constantine, and indeed long afterwards, were circular in the interior, though, like the temple built by Diocletian at Spalato, they were sometimes octagonal externally. This, however, is a Polygon both internally and on the outside, and the mode in which the dome is placed on the polygon shows the first rudiments of the pendentive system, which was afterwards carried to such perfection by the Byzantine architects, but is nowhere else to be found in Rome. It probably was for the purpose of somewhat diminishing the difficulties of this construction that the architect adopted a figure with ten instead of eight sides.
228. Plan of Minerva Medica at Rome, as restored in Isabelle’s ‘Édifices Circulaires,’ on the theory of its being a Bath. Scale 100 ft. to 1 in.
229. Section of Minerva Medica (from Isabelle.) Scale 50 ft. to 1 in.
