The Polyanio Conservatory is probably the oldest building in Kilkis. Built in 1853, it was part of the building complex of the Catholic Monastery of Kalograion and, until the liberation of the city, functioning as a meeting place for Catholics and Christians who accepted the catholic religion in Kilkis. After 1913 it was turned into a headquarters of the allied forces of the First World War, then it became a hospital and in 1991 it was given to the Kilkis Diocese. After the restoration of the building, it operates today as a music school, housing in its premises, a total area of about 600 sq.m. on two floors, the Polyanio Conservatory.