In the Middle Ages, four of the Marian hymns composed during that time were added to the various daily offices said by orders such as the Benedictines, Franciscans and Dominicans, and were then added to all the Church's daily office. Today they are still quite popular in church prayer, Catholic as well as other Christian denominations, and are sung in Latin, especially at the end of Vespers or Compline. Each one is sung at a specific time of the liturgical year.
The "Alma Redemptoris Mater" was mentioned in Chaucer's Canterbury Tales; "Ave Regina Caelorum" is what we're singing presently, and will continue through mid-Holy Week; legend has it that St. Gregory the Great heard angels chanting the "Regina Caeli" one Easter morning and was inspired to write another line to it; and the "Salve Regina", Hail Holy Queen, is perhaps the best known of the four, and has many translations and melodies besides the original.
You can hear us singing one of these, a cappella, every Saturday night and on special Marian feasts.
Here our Sisters sing another Marian hymn, one that is sung every day at the end of Vespers, the Magnificat.
And then, for a change of pace, we have this "Salve Regina" from Sister Act!