The large columns about the main hall, with a diameter of more than 3½ feet, must have been at least 32 or 33 feet high; the attached half-columns with the columns at the entrance and at the rear, including the Ionic capitals, were probably not more than 20 feet high. But assuming that the roof of the corridor was flat, the walls must have been as high as the entablature of the large columns, and so must have extended above the entablature of the half-columns; considerable portions of this upper division of the walls remain. Along the walls on the ground are to be seen a number of capitals, fragments of shafts and bases belonging to a series of smaller columns with a diameter of 1.74 feet, all found in the course of the excavations. They are of tufa, coated with white stucco; they can belong only here, and by the study of their forms--columns, half-columns, and peculiarly shaped three-quarter-columns--the upper division of the walls can be restored with some degree of certainty. Not to go into technical details, in the upper part of the side walls a section of wall containing a window alternated with a short series of columns in which the columns, for the sake of greater solidity, were set twice as close as the half-columns in the lower division of the wall, the intercolumniations being left entirely open (Fig. 25); over the entrances at the front the wall was continuous but was divided into sections by half-columns corresponding with the columns below, a window being placed between every two half-columns in order to conceal the difference in width between the sections of wall at the front and those at the sides. The arrangement was similar at the rear, on either side of the tribunal, as may be seen from the section (Fig. 27). [Illustration: Fig. 25.--Exterior of the Basilica, restored.] With this restoration of the outer walls completed we are able to form a clear idea of the appearance of the main hall. Whether or not the rafters could be seen from below is uncertain, but the probability is that, as assumed in our restoration (Fig. 26), they were hidden by a coffered ceiling. The simple and beautiful interior abounded in fine spatial effects. The corridor and main room were almost as high as the main room was wide, that is between 35 and 40 feet. The light streaming in through the openings in the upper portion of the walls was evenly distributed throughout the hall; we may assume that when the sun became too hot on the south side it could be shut out by curtains.