Pirro Ligorio (1513-1583), painter, architect and antiquarian, was a contemporary and rival of Vasari and Michelangelo, whose position as architect of St. Peter's he inherited in 1564. His best known works are the Casino of Pius IV in the Vatican and the gardens of the Villa d'Este at Tivoli. He also wrote a staggering number of unpublished manuscripts on the antiquities of Rome which have been raided and reviled in equal measure ever since, and are largely responsible for the clouded reputation of the artist which, despite attempts to resuscitate his critical fortunes over the last fifty years, follows him to this day. Judging by Giovanni Baglione's first biography of the artist, published in his 'Lives of the Painters, Sculptors and Architects, etc' in 1642, such negative opinions, however, were not always held, and this paper analyses Baglione's biography in order to record the respect and admiration with which he was evidently viewed in mid-seventeenth-century Rome.