 Complete the following phrase:  The most imposing Italian palace of the 16th century, according to Sir Banister Fletcher, this palazzo was designed by Antonio da Sangallo the Younger, one of Bramantes assistants in the design of St. Peters and an important Renaissance architect in his own right. Construction began in 1515 after one or two years of preparation, and was commissioned by Alessandro Farnese, who had been appointed as a cardinal in 1493 at age 25 and was living a princely lifestyle. Work was interrupted by the 