The first performance of an ancient tragedy took place in 1867. The Odeon has served as a venue for concerts and public events ever since. In September 1920, Manolis Kalomiris presented the “Leventia Symphony” to celebrate the signing of the Treaty of Sèvres. Prime Minister Eleftherios Venizelos was in attendance. During the dictatorship of Ioannis Metaxas (1936-1941), the Odeon was used regularly to perform ancient Greek plays and concerts. Maria Callas sang in the Odeon at the beginning of her career as a member of the Greek National Opera. Since 1955, the Odeon has been the main venue of the Athens Festival.