In 1459 Pius II commissioned Rossellino to design the perfect palazzo for his papal court. The architect took Florence's Palazzo Rucellai by Alberti as a model and designed this 100-room palace. Three sides of the building fit perfectly into the urban plan around it, while the fourth, looking over the valley, has a lovely loggia uniting it with the gardens in back. Guided tours departing every 30 minutes take you to visit the papal apartments, including a beautiful library, the Sala delle Armi (with an impressive weapons collection), and the music room, with its extravagant wooden ceiling forming four letter Ps, for Pope, Pius, Piccolomini, and Pienza. The last tour departs 30 minutes before closing.