1 May is International Workers’ Day. In Poland, it also marks the anniversary of the country’s accession to the European Union. On 1 May 2004, Poland officially became a member of the European Union under the terms of the Accession Treaty signed earlier. It was one of the most significant moments in the country’s modern history, opening up new opportunities for development, community and Poland’s presence in a united Europe. In Gdańsk, to mark the occasion, a march took place through the city’s streets, during which participants carried the flags of Poland and the European Union.