The Te Deum - the classic hymn for Thanksgiving. One story had St Ambrose spontaneously singing it in thanks for the end of a siege. Another for the baptism of St Augustine. The Historical Companion to Hymns Ancient and Modern says “it is now accredited to Nicetas, bishop of Remesiana; (4th century)”
A plenary indulgence for New Year’s Eve.
A half-remembered anecdote from a biography of Pope Benedict XVI, when he arrives home after the war, he first heads to the piano to play the Te Deum.
This is a great one to know.
This version is the simple version - it makes a good start.