Solemnity of the Immaculate Conception is a Holy Day of Obligation. Masses in our Basilica will be at: 6:00 am in English, 7:00 am in Polish, 8:00 am in English, 5:30 pm in English and 7:00 pm in Polish.
The doctrine of the Immaculate Conception is the doctrine that the Virgin Mary was conceived without original sin. The doctrine was almost universally believed over the centuries but was only formally defined as a doctrine of the Church by Pope Pius IX in 1854. Because it is so old, it is one of the Marian doctrines that Islam shares with the Catholic Church, though of course the theological details are very different.