The Feast of the Annunciation, one of the principal feasts of the Christian church, (and is a Solemnity) is celebrated on March 25 (Lady Day), nine months before Christmas. The first authentic allusions to the feast (apart from the Gelasian and Gregorian sacramentaries, in both of which it is mentioned) are in acts of the Council of Toledo (656) and of the Trullan Council (692). Because its significance is much more than narrative, the Annunciation had a particularly important place in the arts and church decoration of the early Christian and medieval periods and in the devotional art of the Renaissance and Baroque.

Here is a short video on the Annunciation: https://www.churchmilitant.com/video/episode/the-annunciation-25-mar