Sofia National Opera, founded in 1890, is the oldest and most prestigious Bulgarian opera theatre. Drawing upon the tradition of West European and Russian ballet theatre, its founders, singers and producers have established the ensemble method of a permanent troupe of soloists, orchestral musicians, ballet dancers, set design artists and producers. The last produce up to ten premières of classical and modern opera and ballet over a ten-month-season. There are many singers, conductors and directors who have contributed to the professional achievements of the Sofia National Opera. Some great international stars of the world of opera, such as Nicolai Ghiaurov, Ghena Dimitrova, Nicola Ghiuselev and Anna Tomowa-Sintow, took the first steps of their artistic careers on the Sofia stage. Preserving the established traditions, the current directorship of the National Opera further develops various long-term artistic strategies. Works unfamiliar to Bulgarian audiences have been staged and there have been co-productions with foreign partners. As early as the 1940s the National Opera made guest appearances in Germany, and since the 1950s the Opera Theatre has appeared throughout Europe, in Africa, in South America and in Asia, with performances that have included sixty classical and modern opera and ballet productions, as well as special concert programmes. The Opera is co-organizer and host of the Boris Christoff International Competition for Young Opera Singers which was held in Sofia for the sixteenth time in 2000. The Sofia National Opera has made various recordings for different labels, among them Naxos (8.557817), Mega Music, Sony, and MMO, under the direction of conductors including Emil Tchakarov, Nayden Todorov, Boris Hinchev, Ivan Marinov and Rouslan Raychev.