"From his work on the church, Michelangelo knew about the cave-like space under the New Sacristy apse in San Lorenzo. When Papal and imperial troops stormed the fallen Florentine republic in 1530, the artist asked the church prior to let him hide there. Michelangelo was on the run -- charged with treason and ordered to be assassinated by the new Medici mayor of Florence -- because of his work on fortifications for the Republic of Florence.
Overcome by boredom during the six-weeks spent in refuge, the 55-year old Michelangelo used charcoal to draw on the walls. His mind though, was still on work -- in addition to a a self portrait and some caricatures he did preliminary drawings for the Sistine Chapel and statues for the New Sacristy. These doodles would prove helpful in the future -- Pope Clement granted him pardon on the condition the artist agreed to complete the Medici chapel. "