Founded by Cosimo the Elder, this library was extended by Lorenzo the Magnificent. The entrance is via the delightful 15C cloister (left doorway of the San Lorenzo church). Its entrance resembles the exterior of a building. A majestic staircase designed by Michelangelo and built by Ammannati leads to a vast reading room, also by Michelangelo, where some of the 10 000 manuscripts are exhibited in rotation.