Michelangelos architectural commissions included a number that were not realised, notably the façade for Brunelleschis Church of San Lorenzo in Florence, for which Michelangelo had a wooden model constructed, but which remains to this day unfinished rough brick. At the same church, Giulio de Medici (later Pope Clement VII) commissioned him to design the Medici Chapel and the tombs of Giuliano and Lorenzo Medici.[78] Pope Clement also commissioned the Laurentian Library, for which Michelangelo also designed the extraordinary vestibule with columns recessed into niches, and a staircase that appears to spill out of the library like a flow of lava, according to Pevsner, ...xa0revealing Mannerism in its most sublime architectural form.[79]