The greatest achievement of the architects of the Renaissance was perhaps their adaptation of the antique Roman style to the modified needs of secular buildings, of which the Palazzo Pitti at Florence by Brunelleschi is an early and notable example. This creating a form of architecture which perhaps reached its noblest expression in the Palazzo Strozzi, begun in 1489 A.D. by Benedetto da Majano. As previously suggested, climate and local material are essential agents in the formation of style, and from Tuscany stone of large size was easily obtainable. [Illustration: No. 77. Pandolfini Palace, Florence.] The contentious conditions existing in many of the Italian cities, entailing necessity for defence, must also be taken into account, and in connection with the foregoing were responsible for the massive and fortress-like construction of the principal dwellings of this period. In the best examples of these, though columns and pilasters were not employed in the façade, the stories are proportioned as if the orders were used. The crowning cornice, however, is proportioned to the whole, varying in height between one fourteenth to one fifteenth. From Florence the movement spread to Rome and other cities, but Venetian Renaissance indicates undoubted evidence of Lombardic influence. Until the end of the fifteenth century the period was one of experiment, but from 1500 to about 1560 the style may be said to have attained a phase distinct and local. At first the various features, structural and decorative, were frank reproductions from the antique, which were studied and measured, and from which systems of proportion were deduced by various exponents, among whom the names of Vignola, Palladio and Serlio are conspicuous. _Rome_ The Roman version of the Renaissance, as distinct from that of Florence, was less massive, Rome being comparatively free from insurrectionary troubles. Columns and pilasters were used to divide the façade into bays, or in the inner courts, which were frequently arcaded, and the principal entrance became a prominent feature. The founder of the Roman school was Bramante, born in 1444 A.D., originally a painter, who was responsible for the original design of St. Peter’s, at the instigation of Pope Julius II. The partly executed work was found to be too weak to bear the superstructure, and Bramante in the meanwhile dying, Raffaelle, Giocondo and Giuliano di San Gallo, and afterwards Baldazzare Peruzzi and Antonio San Gallo were engaged on the edifice. [Illustration: No. 78. St. Peter’s, Rome.] Finally Michael Angelo was entrusted with the sole conduct, and St. Peter’s in its present form must be credited to him, with the exception of the nave, which was added by Carlo Maderno. Of the secular buildings, the Farnese Palace, the work of San Gallo, is typical of the Roman adaptation of the antique architecture to the altered conditions.