Anja Grebe teaches art history at the University of Erlangen-Nuremberg in Germany. She has taken part in numerous international research projects and exhibitions and has published extensively on medieval and modern art history. Grebe is also the author of The Vatican: All the Paintings. She lives in Erlangen, Germany.

Ross King is the bestselling author of books on Italian, French and Canadian art and history. Among his books are Brunelleschi's Dome, Michelangelo, and The Pope's Ceiling, and Leonardo and The Last Supper. King also serves on the council of Academic Advisors for Friends of Florence, a fundraising charity that ensures the survival of Florence's art and architectural treasures. When not traveling for work or pleasure, he lives in the historic town of Woodstock, near Oxford, with his wife Melanie.