Summary The theatre at Kalydon was excavated systematically in a Danish-Greek collaborative project in 2000-2 and 2011-14, supported by the Carlsbergfoundation. The results from the excavation and other state-of-the-art investigative methods for ancient architecture are now being published in a monograph in the monograph-series of the Danish Institute at Athens. The publication is important for theatre history and for architectural history because the theatre is equipped with an unusual square orchestra. The theatre has been meticulously excavated and all small finds thoroughly processed and studied. A great deal of this material is included in the publication and the complete data material presented in this monograph will therefore help pushing research forward on a number of different fronts.