In 1439 Fra Angelico completed one of his most famous works, the "San Marco Altarpiece" at Florence. The result was unusual for its time. Images of the enthroned Madonna and Child surrounded by saints were common, but they usually depicted a setting that was clearly heaven-like, in which saints and angels hovered about as divine presences rather than people. But in this instance, the saints stand squarely within the space, grouped in a natural way as if they were able to converse about the shared experience of witnessing the Virgin in glory. Paintings such as this, known as Sacred Conversations, were to become the major commissions of Giovanni Bellini, Perugino and Raphael.