Authorities said some 200,000 people were expected to attend the afternoon Mass on Pilsudski Square (search) in downtown Warsaw. Among the dignitaries expected were President Aleksander Kwasniewski (search) and Prime Minister Marek Belka (search).

Workers busily decorated an altar on the square with flowers in the Polish national colors — red and white — and the papal banner's yellow and white. Across Warsaw, national and papal flags with black ribbons fluttered everywhere, signs of an official period of mourning to last until the pontiff's funeral at the Vatican on Friday.

John Paul delivered a famous Mass on the square in 1979 that is credited with giving courage to the anti-communist opposition, which brought about the peaceful end of communism 10 years later.

"We wanted to be with other people in this sorrow," said Anna Plewa, 35, a teacher planning to attend the Mass. In the morning, she and her two young children lit candles and placed flowers at the site.

"He showed us how to live," she said. "Sometimes he scolded us from the Vatican. He made us stop and look into our hearts. Now there will be no one to do this."

In Krakow, the southern Polish city where the former Karol Wojtyla rose from priest to cardinal, about 150,000 young people holding candles marched silently through town Monday night in a show of reverence organized spontaneously by cell phone text messages. Similar processions also took place in several other Polish cities.

Many Poles were leaving by plane, train and bus for Rome to pay their last respects to John Paul.

The mayor of his hometown of Wadowice, Ewa Filipiak, was to depart Tuesday with a sack of soil collected from near his birthplace, the church where he was baptized and other sites linked to his life. Filipiak would present it to Vatican authorities to be buried with him.