A very important advance made by the Romans was the improvement of interior architecture. The halls and portions of edifices to be used were more cared for than ever before; this was sometimes done at the expense of the exteriors, to which the Greeks had devoted all their thought. In fact, many ancient Roman temples were inferior to other edifices which they built. The Pantheon is the only one existing in such a state as to be spoken of with satisfaction. [Illustration: FIG. 62.--GROUND-PLAN OF PANTHEON. _Rome._] This ground-plan (Fig. 62) shows that the Pantheon is circular with a porch. Taken separately, the rotunda and the porch are each fine in their own way, but the joining of the circular and angular forms has an effect of unfitness which one cannot forget even when looking at that which we regard with reverent interest. The central portion was at first a part of the Baths of Agrippa, but on account of its great beauty it was changed by Agrippa himself into a temple, by the addition of a row of Corinthian columns around the interior. (See Fig. 63.) [Illustration: FIG. 63.--INTERIOR OF THE PANTHEON.] Taken all in all, the effect of the Pantheon is that of grandeur and simplicity. When we remember that sixteen hundred and eighty-eight years have passed since it was repaired by Septimius Severus, we wonder at its good preservation, though we know that it has been robbed of its bronze covering and other fine ornaments. An inscription still remaining on its portico states that Marcus Aurelius and Septimius Severus repaired this temple; history says that Hadrian restored it after a fire, probably about the year 117, and it is even said that Agrippa, who died A.D. 13, added the portico to a rotunda which existed before his time. The objects now in the interior of the Pantheon are so largely modern that they do not belong to this portion of our subject, but there is much interest associated with this spot, and it is dear to all the world as the burial-place of Raphael, Annibale Caracci, and other great artists. Next to the temples of Rome came the Basilicas, of which there were many before the time of Constantine. The word basilica means the royal house, and these edifices were first intended for a court-room in which the king administered his laws; later they became markets, or places of exchange, where men met for business transactions. The ruins of the Basilicas of Trajan and Maxentius, two of the finest of these edifices, are in such condition that their plans can be understood (Fig. 64). They were large, and divided into aisles by rows of columns; at one end there was a semi-circular recess or apse, in which was a raised platform, approached by steps, also semi-circular in form. Upon this platform the king or other exalted officer had his place, while those of lesser rank were on the steps below, on either side. Fronting the apse was an altar upon which sacrifices were offered before commencing any important business.