Romanian Patriarchal Cathedral Choir "Tronos" performing "The Lord's Lamentations" (Jesus Christ's funeral service, held in the Romanian Orthodox Church, on the day of Holy Friday, before the great and Holy Feast of Pascha).
The text of the Lamentations may have been composed by St.Theodore the Studite (+ 826) himself. The melody is a different story. Initially it was a broader version, but the current one dates from the 18th century. In Greek, it is slightly different. The Russians don't sing the Lamentations, but read it instead.