When closed, the doors of the tabernacle display the Annunciation painted in monochrome and on the back a skull or memento mori, a reminder to the faithful of our common destiny. When open it reveals on the central panel the Virgin enthroned nursing the Child. On the left-hand panel, Saint Catherine of Alexandria is kneeling on the spiked wheel of her martyrdom. On the right-hand panel, Saint Barbara is kneeling on her father Dioscurus, who was her executioner, while in the background we see the tower in which he imprisoned her. In the landscapes there are scenes of the martyrdom of two saints. The abbreviation “ MD” on the frame is probably the date of the work (1500). The tabernacle is an early masterpiece by Mariotto Albertinelli.