Inside the Church of S. Frediano there are two neighbouring chapels, called Chapel of Our Lady of Aid and Chapel of S. Zita or Fatinelli Chapel. At the beginning they were part of the cemetery of S. Caterina. The current appearance of the Chapel of S. Zita dates back to the 17th century.

It is one of the most ancient chapels of the basilica and was built in the part of the cemetery where S. Zita was buried in 1278. In 1611, after that Paolo Guidotti came back to Lucca, he painted a canvas for the altar (3,20 x 1,60 meters), entitled "S. Zita and the Poor", which depicts S. Zita, offering some water to the pilgrim.
Around it there are five canvases, representing the "Miracles of S. Zita", which were painted by Francesco del Tintore in the 2nd half of the 17th century.

In the part of the church, which was used as a baptistery, there is the holy water fountain, made up of a circular basin (with a diameter of 2,55 meters and 3,30 meters high), which was built by Maestro Roberto in the 12th century.

Some documents, which date back to 1173, lead us to think that the baptismal font filled up already with water. Inside it there is a little basin, laying on a pillar, which is crowned by little columns and a lid. On the outside basin there are a high-relief, depicting Scenes from the life of Moses, and some other sculptures, carved by very famous artists, such as a Lombard author, who put the people into relief without carving any architecture element and Maestro Roberto, who carved seven figures, signing his works on the edge of the basin (his style is characterised by the slimness of the human bodies and the little arches, carved drawing inspiration from Roman sarcophagi). Another master, who came from Tuscany and was very closed to Biduino, worked on this masterpiece, carving the internal basin and the lid. The baptismal font, discomposed in 1700, was finally recomposed in 1952.