The Feast of the Immaculate Conception of the Blessed Virgin Mary is celebrated on December 8th. It is a Holy Day of Obligation but this year falls on a Sunday.
Many people wrongly believe that the feast celebrates Jesus’ conception, but in fact it celebrates Mary’s Immaculate Conception; the fact that Mary was, from the very first moment of her existence (her conception), without sin, and chosen to be the Mother of Jesus.
From the moment of her conception, Mary was perfect; she was sinless.
Every Dec. 8th the Pope goes to the Spanish Steps in Rome to commemorate the definition of this doctrine in 1854. A fireman of the Rome Fire Brigade climbs a ladder and places a wreath of flowers on the arm of Our Lady above the Steps.
The History and Doctrine of the Feast. – catholicireland.net
Planning a Mass in school for the Feast – catholicbishops.ie