The Dominican's Siena home is an enormous, severe, and vaguely unattractive pile of bricks (1226), jutting above a modern section of town. There are good views here, though, of the Duomo and Siena's rooftops. The raised chapel off the west end (to the right as you enter) preserves the only genuine Portrait of St. Catherine, painted by her friend and contemporary Andrea Vanni.

The Cappella di Santa Caterina (Chapel of St. Catherine) halfway down the right wall was frescoed with scenes from the saint's life. All except the right wall (where in 1593 Francesco Vanni painted Catherine performing an exorcism) were frescoed by Sodoma in 1526. The large work on the left wall of her interceding on behalf of a condemned man as well as the other scenes of her in ecstasy and swooning are some of Sodoma's best work. The focal point of the chapel, however, is Catherine's venerated head, in a gilt reliquary case, on the altar.

At the end of the nave, on the right, is an Adoration of the Shepherds by Francesco di Giorgio Martini, dominated by a crumbling Roman triumphal arch in the background and a Pietà above. The first chapel to the right of the altar is home to a Madonna and Child with Saints by Matteo di Giovanni, one of whose masterpieces, St. Barbara Enthroned with Angels and Sts. Mary Magdalene and Catherine (1479), is in the second chapel of the left transept.