Originally located on the historic Via Francigena, the Taja Chapel was created as a place of private devotion and representation for the illustrious family of the same name. The del Taja family, originally from Lombardy, moved to Siena in 1350 and became rich through trade, earning a place of prominence among the city's most important families. The ornamentation of the chapel is thought to be the work of Giulio del Taja, a prominent figure in Siena between the 17th and 18th centuries, a member of the Knights of St Stephen and Provveditore alle Fortezze of the city.
Despite its small size, the chapel has an aisle, a presbytery and an altar, all embellished with frescoes, monochromes on canvas, white stucco, faux-root paintings and stucco reliefs. Above the altar depicts the Assumption of Mary surrounded by a group of Apostles around the tomb, as well as God the Father and Jesus in stucco and a number of saints painted in fresco against the blue background of the sky. Originally, a small window at the top illuminated the reliefs, emphasising the overall scenic effect. The walls, enclosed by eight stucco frames, are adorned with half-length portraits of Sienese saints and blesseds.