Lamentatio sanctae matris ecclesiae Constantinopolitanae

Lamentatio sanctae matris ecclesiae Constantinopolitanae ('Lament of the Holy Mother Church of Constantinople') is a motet by the Renaissance composer Guillaume Dufay. Its topic is a lament of the fall of Constantinople to the Ottoman Turks in 1453. Because of its Byzantine subject matter, it is sometimes grouped together with Vasilissa ergo gaude, Apostolus gloriosus and Balsamus et munda cera as one of Dufay's "Byzantine motets".