In seeking guidance from the antique two monuments in particular appear to have appealed to him as offering appropriate suggestions, the Pantheon and the Basilica of Maxentius, then called the Temple of Peace. The first of these monuments gave the model for a mighty hemispherical vault securely suspended over a vast area, while the second offered an example of a stupendous system of piers and arches. In maturing his great scheme with these models before him, he conceived the idea of uniting their respective sublimities, and is said to have boasted that he would set the Pantheon upon the arches of the Temple of Peace. While it is probable that the majestic elevation of the dome of Florence haunted his imagination, and led him to feel that he must lift his dome high, he wished, at the same time, to give the design a more classic character, and a sounder structural form. In striving to accomplish this double purpose Bramante produced a scheme for an elevated dome of almost thoroughly Roman character, and at the same time of imposing external effect. The architect Serlio gives an illustration[40] (Fig. 23) of this project which is highly instructive.[41] A comparison of it with the scheme of the Pantheon shows a close likeness in essential forms and adjustments. The points of difference are mainly such as Bramante’s desire to make his dome externally conspicuous would require. In the Pantheon (Fig. 24) the dome springs from within the massive drum at a level far below the external cornice, so that the wall above the springing forms a solid and powerful abutment, reaching almost to the haunch of the vault. Above this a stepped mass of masonry, diminishing in thickness as it rises, is carried well over the haunch, effectively overcoming any tendency to yield to the force of thrust. A Corinthian order, surmounted by an attic, is carried around the wall of the interior,[42] while the wall on the outside is plain. [Illustration: FIG. 24.--The Pantheon.]