We have worked as design consultants to the Board of OMMA defining the employer’s requirements for the two main halls in this new international conference centre. The buildings are linked directly to the adjacent Megaron Concert Hall.The Alexandra Trianti Hall has a seating capacity of 1,600,with two upper tiers and dedicated translation booths. It is designed to accommodate grand opera as its second major use. Extensive stage machinery and fl ying facilities are provided.Rusticated stone walls define the overall geometry of the room. Bronze fins frame the proscenium and provide important early acoustic refl ections. The patinated copper and bronze side tiers are placed in front of a cherry veneer wall, adding a sense of warmth to the audience enclosure. The ceiling reinterprets a traditional dome in a contemporary form, recognising acoustic demands and the need for concealed technical lighting.The Nikos Skalkotas Hall seats 400 and is used for conference, education, small scale drama and music recital. The internal treatment of the space is subdued, responding to the wide range of intended uses. Swiss pear and maple veneers linethe walls, which continue to form an acoustic shell when required. The ceiling works in the manner of a theatrical gauze, appearing almost solid when lit from below, while concealing lighting and acoustic absorbency.