ENI SANCTE SPIRITUS, often known as the “Golden Sequence” is one of the great jewels of the Church, prescribed for the Pentecost Mass and its octave (not including the following Sunday.)
Jeff Ostrowski recently made available several versions of the score, including a beautiful (optional) organ accompaniment which you can listen to here:
SECONDLY, HERE IS MY SETTING IN ENGLISH, which uses the translation by Edward Caswall from the Lyra Catholica. Included (in one file) are separate versions for organ or piano and with optional lower key.
Happy Birthday to the Church!