It consists of a large octagon surmounted by a dome and preceded by a lofty vaulted atrium or vestibule.

The single round arch of this vestibule repeats the _testudo_ of a Roman bath, and the decorative details are accurately reproduced from similar monuments.

Unfortunately, Giorgio Vasari, who was employed to finish the cupola, spoiled its effect by raising it upon an ugly attic; it is probable that the church, as designed by Vitoni, would have presented the appearance of a miniature Pantheon.

At Rome the influence of Bramante was propagated through Raphael, Giulio Romano, and Baldassare Peruzzi.

Raphael's claim to consideration as an architect rests upon the Palazzi Vidoni and Pandolfini, the Cappella Chigi in S.Maria del Popolo, and the Villa Madama.