The church of Santa Maria della Rotonda is located in the northwest part of the Palazzo. It was first documented in 1131, and was included in the sale of the Augusta Fortress in 1322 by Castruccio Castracani, Lord of Lucca. In 1428, it was aggregated to the nearby church of Sant’Alessandro Maggiore. It was the former home of the Tailor’s Company Association, and then of the Misericordia. The current building had been restructured sometime in the late-1700s and early-1800s. This is when the internal vault was frescoed by Ippolito Marracci. In the vault, he created fake architectural elements and a depiction of the Madonna. In 2000, the chapel was restructured for the Jubilee, and since then, has housed the permanent archive collection of Paolo Cresci on the history of emigration.