Baptistery of San Giovanni alle Fonti, Early Christian baptistery in Milan, Italy

The Baptistery of San Giovanni alle Fonti survives only as ruins beneath Piazza del Duomo in Milan. It was an octagonal building with a diagonal of 19.3 m and sides of 7.4 m, and walls 2.8 m thick. Eight niches, four rectangular and four semicircular, opened along the perimeter, separated by columns of red porphyry 3.6 m high.

The building was created during the early period of Christianity as a place for baptism ceremonies. A significant moment was the baptism of Saint Augustine by Saint Ambrose at this site.

The baptistery was reserved for men, while women were baptised in the nearby Santo Stefano alle Fonti. Ambrose explained the octagonal plan: the seventh day signifies the Law, the eighth the Resurrection and eternity. The octagon also recalls the eight Beatitudes.

The building is accessible through Milan Cathedral and sits in an archaeological area below the modern city. Wear comfortable shoes as the path involves stairs and corridors.

Baptism was performed by pouring water three times over the head, a specific technique for that time. This practice shows how different religious rituals were in the past.