Not much progress was made during the rule of Niccolò III as he focused more on political matters and economic prosperity within Ferrara. Leonello was a skilled politician and was responsible for the construction of the first hospital of Ferrara. But he distinguished himself chiefly as a man of culture. Leon Battista Alberti wrote his "De Re Aedificatoria" at Leonello's commission, and at the Ferrarese court there worked artists such as Pisanello, Iacopo Bellini, Giovanni da Oriolo, Andrea Mantegna, Piero della Francesca and the Netherlandish Rogier van der Weyden. His personal breviary was sold in a fragmented state in 1958 by Baron Llangattock at Christie's. It has since then been known as the Llangattock breviary. It was created under the artistic direction of Giorgio d´Alemagna and painters like Matteo De Pasti and Jacopo Magnanimo contributed to it. Leaves from it are in the collections of museums such as the Louvre in Paris, the Danish National Library, and several private collections.