In February 1994 Peter Phillips and the Tallis Scholars performed Antonio Allegri's Miserere mei, Deus on the 400th anniversary of the death of Palestrina in the Basilica of Santa Maria Maggiore, Rome, where Palestrina had trained as a choirboy and later worked as Maestro di Cappella.
The tenors sing with one voice, the soprano hits inhuman notes; it is musical perfection and could be, for me, the most beautiful music ever written. I love choral music more than any other, from the soul-soothing beauty of Gregorian chants to the amplified pop fun of Perpetuum Jazille and the story of how this score came to be in the public domain is amazing.
The Vatican forbade copies of The Miserere from being made to preserve its rarity, threatening the makers of any copy with excommunication. But in 1770, 14-year-old Mozart attended two performances of the mass at St. Peter's on a trip to Rome with his father and he was able to transcribe it faithfully from memory.