The theatre at Kalydon in Aitolia - known only since a few decades - has already attracted a lot of attention due to its square orchestra and rectilinear benches for seating. The Danish-Greek collaborative project responsible for investigating the theatre presents in this two-volume publication results of the excavation and documentation, including all finds such as tile, pottery, metals and coins, made during the excavations. The traditional analysis of the building is supplemented by an archaeoacoustic analysis comparing acoustic advantages and disadvantages between the square and semicircular design.