PUBLIC HOLIDAYS
During these public holidays the banks and other institutions are predominantly closed, as well as some smaller shops.

January 1: New Year's Day
Easter Sunday and Monday (first Sunday after the first spring full moon)
May 1: Labour Day
May 3: Constitution Day (on the anniversary of May 3, 1791 Constitution proclamation)
Corpus Christi: On Thursday of the ninth week after Easter there are processions with white-dressed children, attended by hundreds of people.
August 15: Assumption of Virgin Mary, Polish Army Day (on the anniversary of the victorious battle of 1920 against Russian army fought on the outskirts of Warsaw)
November 1: All Saints' Day
November 11: National Independence Day (Poland regained independence in 1918 after 123 years of partitions)
December 25, 26: Christmas

There are also less official feasts that are usual working days:

Fat Thursday: The day of eating doughnuts (the last Thursday of the Carnival)
International Women's Day: a popular communist feast when men should show their appreciation of women with a flower or a gift. Originally the day was established in USA to commemorate 129 women who died during a fire in a New York factory in 1908 (March 8th)
The First Day of Spring: An unofficial occasion popular among children, who traditionally play truant on that day. (March 21st)
April Fool's Day: A world-known tradition of making fools of everyone, in Poland called with latin name "Prima Aprilis". (April 1st)
Child's Day: Children are given the sweets, taken to zoo garden or something similar. (June 1st)
St John's Night: The shortest night of the year is the only time when fern blooms. The one who find it, would be happy and well-off, but be careful: it is forbidden to share hapiness and money with anyone else. (June 24th)
Eve of St Andrew's Day: People read the future from the shapes of wax that was earlier melted and poured into cold water. (November 29th)