The façade of this cathedral was built in two stages. The lower part in polychrome marble was begun around 1284. It is built in Tuscan Gothic style by Giovanni Pisano, replete with gargoyles. Giovanni Pisano worked on the lower levels until 1296, when he suddenly left Siena. At that time, between 1270 and 1285, the nave of the church had been raised and a higher façade became necessary. Work at the façade continued for another fifteen years and was then stopped. Meanwhile in 1288, the rose window, a round glass-stained window set inside a square, was installed in the choir, based on designs by Duccio di Buoninsegna. The three portals, surmounted by lunettes and Gothic pediments, were designed by Giovanni Pisano. The columns between the portals are richly decorated with acanthus scrolls, allegorical figures and biblical scenes. Work on the upper part of the façade only resumed in 1376 under the direction of Giovanni di Cecco, working on a new elaborate design, inspired by the Orvieto Cathedral. It was to be erected much higher than foreseen, because the nave had, once again, been raised. The division of the upper part does not match the division of the lower part. The pinnacles of the upper part do not continue over the columns flanking the central portal. The weight of the elegant side towers was reduced by adding windows. The statues of the lavish façade were sculpted by Giovanni Pisano and assistants. They represent prophets, philosophers and apostles. The half-length statues of the patriarchs in the niches around the rose window are the work of other sculptors. Almost all the sculptures on view are copies. The originals are kept in the "Crypt of the Statues" in the Museo dell'Opera del Duomo. The bronze central door is recent and dates from 1958. It was made by Enrico Manfrini. The scenes on the door represent the Glorification of the Virgin. The three large mosaics on the gables of the façade were made in Venice in 1878. The large central mosaic, the Coronation of the Virgin, is the work of Luigi Mussini. The smaller mosaics on each side, Nativity of Jesus and Presentation of Mary in the Temple, were made by Alessandro Franchi. On the left corner pier of the façade, a 14th century inscription can be found, marking the grave of Giovanni Pisano. Next to the façade stands a column with the she-wolf breast-feeding Romulus and Remus, symbol of Siena (and also of the contrade Lupa). According to legend, Senius and Aschius, sons of Remus, founded Siena. They had stolen the statue of the she-wolf from the Temple of Apollo in Rome.