Among the most valuable items belonging to the Museum is undoubtedly the fragmented head from the Crucifix made by Lando di Pietro in 1338, the only known wooden sculpture of this Sienese artist, goldsmith and architect. The author and dating were discovered in a very peculiar way through the crucifix’s troubled history: once located on the church altar, it was split into pieces by the 1944 bombing; the broken sculpture revealed a parchment in the hollow of Christ’s knee, bearing the date and the name of the author, in which he commended his soul to God. A second larger parchment was discovered in the sculpture’s head, containing a prayer, the author's name and exact date in which this work had been carried out. Both parchments are currently on display in the museum.