Saint-Jean-Baptiste church, the largest in Corsica, was built between 1636 and 1666. The bell towers on the façade were added late in the 19th century.
The interior of the sanctuary is adorned with numerous works of art, including the silver tabernacle on the high altar, carved in the 19th century by the Sienese silversmith Gaetano Macchi. Above the 18th-century marble statue of Saint John the Baptist, there is a surprising stucco group depicting the Circumcision of Christ. The imposing “swallow's nest” organ loft, dating from 1742, is decorated with three paintings depicting scenes from the life of Saint John the Baptist. Saint John's Day is associated with the summer solstice and is celebrated with a bonfire, a reminder of its pagan origins. In Bastia, on the evening of 23 June, a huge bonfire is lit beneath the ramparts of the Citadel on the edge of the Old Port basin. Associated with this fire festival is the ritual of taking your first dip in the sea, which on this day is said to have regenerative properties.