This publication offers a comprehensive presentation of the architecture of the theatre at Kalydon in Aitolia, which was excavated recently in a Danish-Greek collaborative project. The volumes contain main chapters on the architecture with detailed plans, sections, photographs, and reconstructions, as well as thorough presentations of the small finds, such as coins, pottery, glass, metals, and figurines found in the excavations of the theatre. The publication also includes special studies on the theatre’s acoustic properties and an anthropological study of the osteological evidence from a Byzantine grave. The theatre, dating to the Classical and Hellenistic periods, is unique among ancient Greek theatres due to its unusual pi-shaped auditorium, and its place in the general development of ancient Greek theatres is discussed in great detail. This publication of a unique building in ancient Greek architecture will not only enhance our knowledge on ancient Greek theatre architecture in general but also add new evidence pertaining to the activities of the ancient Kalydonians and the historical development of their city.