With regard to seventeenth- and eighteenth-century Roman festival culture, numerous documentary testimonies provide evidence of liturgical celebrations accompanied by polychoral music. Diaries, diplomatic notes and official accounts of solemn liturgies (especially extant lists of participants) refer to a musical framework of four, six or even eight choirs for special occasions. Among these records, however, performances with a full dozen single choruses are extremely rare. The best-documented case is Agostini’s performance with twelve choirs for second Vespers at St Peter’s Basilica on 29 June 1628, the patron saints’ day. The symbolically arranged ensemble ¹ consisted of at least 146 participants. ²