The first external chapel in the left aisle is dedicated to St Catherine of Alexandria. It was designed for the Cesi family by Guidetto Guidetti in about 1550, although it is thought that Martino Longhi the Elder was also involved. The family had a strong interest in the church of Santa Caterina dei Funari, hence the dedication. Their crest of a tree over stylized mountains features in the heraldry here. The chapel later passed to the Massimo family, and their heraldry also features.