Up to 300,000 came to Pilsudski Square, the site of an inspirational papal mass during John Paul's first visit as pope to his homeland in 1979.
Activists from the anti-communist Solidarity trade union movement say that visit was a turning point in Polish history, inspiring millions to join the protest movement that played a key role in ending communist rule in Poland and the rest of central and eastern Europe.
President Aleksander Kwasniewski and Prime Minister Marek Belka joined the crowds for a gathering filled with sadness at the loss of a national icon.
Poland will remain in an official state of mourning until the pope's funeral in Rome Friday.
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