It is a tall composition in white and black marble spanning the concave wall of the apse behind the ciborium of the main altar. Standing on a lofty plinth, four Tuscan columns with black shafts carry a broken Doric beam. Between the columns are niches with figures of St Nicholas (patron saint of Bari) and St Stanislaus (patron saint of Poland). Against the backdrop of the noticeably wider central niche, a black sarcophagus rests on sculptural lion's feet, on which the figure of the Queen kneels. Bona is depicted realistically as an elderly person. Below the sarcophagus, at the level of the main pedestal, is a pedestal and on it a black marble slab with a now illegible inscription. It is flanked by two semi-recumbent allegorical female figures with (also barely legible) coat-of-arms cartouches. It is most likely that the figure on the left, wearing a royal crown with tendrils, is an allegory of the Republic. Both the architectural structure of the tomb, with its calm composition and exquisite proportions, and the sculptural elaboration of the Queen's figure, with its deep but rather classical modelling of her robes, attest to the high artistry of the author of this monument. Unfortunately, as a result of works carried out at the beginning of the 20th century, the present appearance is somewhat impoverished compared to its earlier state. The bas-relief depicting the Resurrection of Christ, which was added after the tombstone's creation, and the fresco covering the wall depicting figures of Polish saints and kings were removed. Nevertheless, Santi Gucci's work is a striking artistic accent in the interior of the basilica. The sepulchral monument was erected in the basilica in 1593 by the sculptor Andrea Sarti of Carrara and his two assistants: Francesco Zaccarella and Francesco Bernucci.