The beginning of May means 3 days off for most Poles.
1st May has always been Labour Day, officially celebrated by all communist states in times of Cold War. Poles also attended it - sometimes willingly, sometimes forced. When Poland regained sovereignty in 1989, the authorities didn`t annul the holiday. Even today left parties call their members and supporters to take part in demos.
2nd May is the day of the Polish flag - a new holiday introduced after 1989.
3rd May - Constitution Day, to celebrate the first constitution in Europe and second after the USA. There are mass services, parades, performances, wreaths etc.