1636, reportedly uncovered by Remo Giazotto in the late 1960s but no longer traceable since at least the mid-1970s: It must be noted that no image of the theatre of 1637 is extant today: neither of the outside nor of the inside. What is well known is that the Teatro San Cassiano was inaugurated in 1637 with the performance of L’Andromeda by Francesco Manelli (music) and Benedetto Ferrari (libretto). The dedication, dated 6 May 1637, specifies that the opera “had been reborn on stage two months ago”. The historical significance of this event is incalculable, as is the commercial practice established of purchasing of an entrance ticket by each spectator; a concept destined for global diffusion, but which occurs here as public opera for the first time. Indeed, the Teatro San Cassiano can, therefore, be seen as the economic-architectonic prototype of the Italian opera house destined to enjoy enormous fortune over the following centuries. The structure of the theatre of 1637 Given the total absence of images relating to this phase of Teatro San Cassiano’s history, a document stipulated by the Notary Alessandro Pariglia, dated 12 February 1657 more veneto, offers significant insight with regard to the internal structure of the auditorium. In it, the Notary records that before this date there were a total of 153 boxes in the theatre, but that now there remained 102; no reason is given and whether he is referring to the number of boxes in use or their number in total is not clear. The same number of 153 was later described by the French Jacques Chassebras de Cramailles in 1683, who wrote in the Mercure Galant that “the theatre of San Cassiano [...] has five tiers of boxes and 31 in each tier”. Noting the characteristics of Venetian theatres in the seventeenth century, it is therefore logical to conclude that the total of 153 boxes is made up of four tiers of 31 boxes each, plus a first “ground-floor” tier, known as the ‘Pepiano’, of 29 boxes with two side-entrances to the “platea” (orchestra stalls). This number matches precisely that recorded, decades later, by the Venetian architect, Francesco Bognolo, when he carried out surveys of all Venetian theatres (plus one in Padua) prior to 7 June 1765. In his list of measurements relating to what Bognolo calls the “old Teatro San Cassiano” (dating back to 1696 or further to 1670), the architect