Engaged cassetta frame on a polyptych panel ca. 1380 Siena Siena Information on Niccolò di Buonaccorso (active 1356, d. 1388) is sparse, but this 'Coronation of the Virgin' is thought to be part of a portable altarpiece he painted circa1380. Two other panels with scenes from the life of the Virgin in a similar style and size and with similar frames are in the Uffizi, Florence and the National Gallery, London. The engaged frame on the Lehman panel has an intact patina. The London frame, unfortunately, no longer has its original surface. On all three frames there is no frieze between the ogee on the top edge and the cavetto on the sight edge of the principal molding, though the pastiglia spandrel give the sense of one. The outer molding supports the cusped pastiglia arch with a strength usually seen in tabernacle frames with pilasters. On the Florence and London panels the arch reflects the architecture depicted in the painting. On the Lehman panel the cusps repeat the curves of the conc