The Teatro San Cassiano (or Teatro di San Cassiano and other variants) in Venice was the world’s first public opera theatre, inaugurated as such in 1637. The first mention of its construction dates back to 1581. The name with which it is best known comes from the parish in which it was located, San Cassiano (Saint Cassian), in the Santa Croce district (‘sestiere’) not far from the Rialto. The theatre was owned by the Venetian Tron family and was the first ‘public’ opera house in the sense that it was the first to open to a paying audience. Until then, public theatres (i.e., those operating on a commercial basis) had staged only recited theatrical performances (commedie) while opera had remained a private spectacle, reserved for the aristocracy and the courts. The Teatro San Cassiano was, therefore, the first public theatre to stage opera and in so doing opened opera for wider public consumption. In 2019 a project, conceived by the English entrepreneur and musicologist Paul Atkin, was announced to reconstruct in Venice the Teatro San Cassiano of 1637 as faithfully as academic research and traditional craftmanship will allow, complete with period stage machinery and moving stage sets. The project aims to establish the reconstructed Teatro San Cassiano as a world-renowned centre for the research, exploration and staging of historically-informed Baroque opera. Sixteenth century The first information relating to a theatre on this site dates back to 1581. The Tron family theatre for commedie is referenced both in a letter sent by Ettore Tron to Duke Alfonso II d’Este, dated 4 January 1580 more veneto (i.e., 1581), and in Francesco Sansovino’s, Venetia città nobilissima et singolare, in which two theatres in the parish of San Cassiano are mentioned: according to some historians, and based on the roughly rectangular shape of the plot of land on which it stood, the Tron theatre would appear to have been the “egg-shaped” one, with the Michiel in turn being the “round” one. In the cited letter, Tron writes of “expenditure of great significance for the recitation of comedies”, but he also hints at the popularity of his venture: Other than suggesting that the theatre was well received, this also confirms that theatre-boxes, which would later constitute one of the key architectural elements of the théâtre à l'italienne (an Italianate opera house), were already present in this first incarnation of the venue. This too is confirmed