There are no sketches or documents relating to the Sistine Madonna's composition, but the museum fills this gap by exhibiting several other Raphaels, including the famous portrait (on loan from the Uffizi) of a melancholy Julius II slumped in his red throne and a portrait of the noblewomen Donna Velata, whose noble features may have inspired Raphael's depiction of Mary in the Sistine Madonna.

WSJ: The Sistine Madonna | Old Masters Picture Gallery | The Madonna Above the Cherubs | By A.J. Goldmann