Throughout this building the details of the architecture are unsurpassed for variety and elegance by anything found in the metropolis, and are applied here with a freedom and elegance bespeaking the presence of a Grecian mind even in this remote corner of the Empire. Another interesting feature is the porch. This was supported by four slender columns of singularly elegant design, but placed so widely apart that they could not have carried a stone entablature. It is difficult to guess what could have been the form of the wooden ones; but a mortice which still exists in the walls of the temple shows that it must have been eight or ten feet deep, and therefore probably of Etruscan form (Woodcut No. 167); though it may have assumed a circular arched form between the pillars.[167] [Illustration: 189. View of the Interior of the Temple of Diana at Nîmes. (From Laborde.)] Another peculiarity is, that the light was introduced over the portico by a great semicircular window, as is done in the Buddhist caves in India; which, so far as I know, is the most perfect mode of lighting the interior of a temple which has yet been discovered. Not far from the Colosseum, in the direction of the Forum, are still to be seen the remains of a great double temple built by the Emperor Hadrian, and dedicated to Venus and Rome, and consisting of the ruins of its two cells, each about 70 ft. square, covered with tunnel-vaults, and placed back to back, so that their apses touch one another. These stand on a platform 480 ft. long by 330 wide; and it is generally supposed that on the edge of this once stood 56 great columns, 65 ft. in height, thus moulding the whole into one great peripteral temple. Some fragments of such pillars are said to be found in the neighbourhood, but not one is now erect,—not even a base is in its place,—nor can any of its columns be traced to any other buildings. This part, therefore, of the arrangement is very problematical, and I should be rather inclined to restore it, as Palladio and the older architects have done, with a corridor of ten small columns in front of each of the cells. If we could assume the plan of this temple to have been really peripteral, as supposed, it must have been a building worthy of the imperial city and of the magnificence of the emperor to whom its erection is ascribed.