The Baptistery of San Giovanni stands to the left of the Cathedral. Built probably on the remains of a pagan temple in the 7th century, it remains the only example of Romanesque construction in Treviso. The building has undergone multiple renovations and restorations, regaining its original appearance only in 1935. For centuries, the building was the only city baptistery, but from its rectangular plan, it is assumed that it was originally designed as a church.
The main façade is characterized by a lunette featuring a bas-relief from the 14th century, depicting the Decollation of Saint John the Baptist, while on the side facing the Cathedral, between two windows, there are traces of a Christ risen, painted by Tiziano Vecellio.
Inside, at the center, stands the remarkable baptismal font in red Verona marble from the late 16th century. The apses are enriched by precious Romanesque-Byzantine frescoes.
