Located just west of Piazza Duomo, a group of buildings are a splendid example of Milan's architectural development from the Medieval to the 1600's. Piazza Mercanti boasts Palazzo della Ragione (1228) Milan's most outstanding building that dates back to the era of the commune system. Across the square, there is the elegant 14th century construction Loggia degli Osii (1316): built in black and white marble, the project was commissioned by Matteo Visconti. Next to the Loggia there is the 18th century Palazzo delle Scuole Palatine, designed by Carlo Buzzi and built between 1644 and 1645. At the end of the square there is the remains of Panigarola House (XV century) which used to house the Status Office. In building number 2 of via Mercanti is Palazzo dei Giureconsulti, commissioned by Pope Pious IV, Angelo Maria Medici of Milan, during the late Reinassance (1561). The tower's central clock, located between the fašade of the Napo Tower, goes back to 1272, and was incorporated in 1601.