Siena’s Baptistery of San Giovanni is a remarkable building. It was actually built more or less underneath the city’s cathedral. In 1317, the Opera del Duomo – that is, the institution in charge of the cathedral – wanted to extend the choir of the Duomo. This was, however, rather difficult. The end of the choir was already near the edge of a steep hill, and the only way to construct a further two bays was to erect a new building whose roof would support the prolonged choir. This was to become the baptistery. The job to build it was entrusted to the capomastro of the Opera del Duomo, Camaino di Crescentino (ca. 1260-1337/8). He was the father of Tino di Camaino (ca. 1285-1337), a sculptor who was responsible for the creation of a set of sculptures for Florence’s baptistery, which is also dedicated to San Giovanni (i.e. Saint John the Baptist). What remains of these sculptures can be admired in the Duomo Museum in Florence.
But now back to Siena. The baptistery was built between 1317 and 1325. The building was provided with a marble facade in the Sienese-Gothic style after 1355. The facade is attributed to Domenico di Agostino (ca. 1315/20-1366), but it was never finished. The top part has remained undecorated. The result is that not the entire apse of the cathedral is covered, but apparently the Sienese had no problems with this situation.
The baptistery’s most prized possession is of course its baptismal font. It was made between 1417 and 1431 and many of the most famous artists of the early fifteenth century provided assistance. The most important panel showing the Baptism of Christ is the work of Lorenzo Ghiberti (1378-1455), while Donatello did the panel depicting the Feast of Herod and was responsible for the statues of Faith and Hope. Both were Florentines. Jacopo della Quercia (ca. 1374-1438), however, was from a small town near Siena. He sculpted the statue of Saint John the Baptist topping the font and several other figures.
The interior of the baptistery is very colourful. The entire vault is frescoed and so are the wall and conch of the apse. Many of the frescoes are the work of Lorenzo di Pietro (ca. 1410-1480), who was nicknamed Il Vecchietta. The name literally means “old woman” and unfortunately we do not know how he acquired this somewhat offensive epithet. Lorenzo was obviously a very good painter. On the wall of the apse he painted scenes showing the Flagellation of Christ, the Annunciation and the Ascent to Calvary. The frescoes in the conch are, however, by a different artist. They are attributed to one Michele di Matteo da Bologna, a contemporary of Lorenzo whose years of birth and death are unknown. The frescoes have presumably been repainted substantially, as they look surprisingly modern. The altarpiece is modern. It is the work of Alessandro Franchi (1838-1914).
Also in the baptistery is a polyptych by Andrea Vanni (ca. 1330/33-1414). It can be found near the right entrance. This large altarpiece was originally in the church of Santo Stefano alla Lizza elsewhere in Siena, but apparently there were reasons to move it to the baptistery. The polyptych shows a Madonna and Child (holding a dove) in the centre, flanked by – from left to right – Saint James the Greater (with a book and staff), Saint Stephen (with the Mickey Mouse ears, which are actually stones), Saint John the Baptist (with the Lartin text ECCE AGNVS DEI) and Saint Bartholomew (with what is presumably a knife; a reference to the story that he was flayed alive). There are many more saints on the panel, but it would serve no purpose to mention them all. The predella of the polyptych is not Vanni’s work. It is attributed to Giovanni di Paolo (1398-1482).