The Annunciation (March 25th) - Zwiastowanie N.M.P.
The Angelus in Poland is a 600 year old custom which is adhered to by everyone.  The Church bells ring to announce the Angelus three times each day, and all interrupt whatever they may be doing to recite the salutation and prayers.  Other names for the Annunciation are M.B. Otwornej (Our Lady of Spring because she opens Spring), M.B. Zagrzewnej (Our Lady of Encouragement), and M.B. Ozywiajacej (Our Lady of Life).