In 1455 he was made a Cardinal by his uncle Pope Calixtus III, and, in 1492 on the death of Pope Innocent VIII, was elevated to the papal chair. Pope Alexander VI---almost certainly elected with bribes, and while not the moral monster of legend---was a man utterly worldly in outlook who became enormously rich at the expense of the church. Already the father of several children, he possibly begot two more while pope. 
His children can be divided into three groups: those born before 1472, those born to Vanozza de' Cataneis between 1475 and 1481, and those after he had become Pope. The influence on him of his favourite son, Cesare Borgia, only made a bad situation worse, further embroiling him in Italian politics and wars. He endeavoured to break the power of the Italian princes, appropriating their possessions for 
the benefit of his own family employing the moxt execrable means to gain his ends. During his pontificate, he apportioned the New World between Spain and Portugal, and introduced the censorship of books. 
His main rival, Cardinal Giuliano della Rovere, a nephew of Pope Sixtus IV and the future Pope Julius II, had passed most of Alexander's pontificate in exile, stripped of many of his benefices. It was Pope Julius II perhaps more than any other single person who set the tone of contemporary and later attitude towards the Borgias. 
Alexander VI died surrounded by an atmosphere of hatred and fear, a hatred so violent that Pope Julius II and all his successors refused to occupy the Borgia apartments in the Vatican, which were then left 
neglected until the nineteenth century. 
 

Source: Leo van de Pas