ROME - A sprawling, sweating campground with more than 2 million swaying, practically delirious fans of Pope John Paul II sprang up Saturday on Rome's outskirts, nuns settling in beside faithful in bikinis for a prayer service with the pontiff.
The 80-year-old pope arrived by helicopter just as a fat, red sun sank above the hilly grounds of the Tor Vergata university campus, where the crowd had gathered for World Youth Day celebrations. The temperature started cooling down from readings that reached 100 degrees earlier in the day when pilgrims were streaming in, almost all by foot, after walking as far as nine miles.
The pope smiled broadly and two youths supported his arms as he shuffled slowly to his ''popemobile,'' which drove him to center stage for the celebration. He was due to head home before midnight, but most of the faithful were planning to bed down for the night in sleeping bags, waiting for him to return early Sunday morning for a farewell Mass.
''We're well over 2 million people,'' Mayor Francesco Rutelli said at the ceremony. The number, based on surveys from police helicopters, was almost double the Vatican's estimate at the start of World Youth Day events on Aug. 15.
Earlier, the sun scorched the grounds while fire hoses, fans and fainting tents worked to relieve countless young pilgrims overcome by heat.
''That. Feels. So. Goooood,'' said Katy Rothman of Somers, N.Y., reveling under the blast of spray that greeted the young woman after a three-hour walk to the campus outside Rome.
World Youth Day - back in Rome this year, after starting there under John Paul 15 years ago - fell on what forecasters projected as the hottest weekend of the year. Hundreds of pilgrims had been treated at the campus by early evening, most overcome by the Roman sun and Mediterranean humidity.
More than a score of faithful needed hospitalization, a few of them for seizures or heart problems, doctors said, but nearly all the heat cases recovered after a half-hour in air conditioned ''fainting tents'' with friends and nurses fanning them.
Elsewhere, young people stripped down to shorts and bikinis around gushing hydrants, splashing in welling mud pools. Woodstock comparisons seemed inevitable.
''It's hot, and I'm going to get wet anyway,'' said Dina Focina, 22, waving a hand at her two-piece.
The outdoors vigil and Mass close a six-day slate of events that brought the hordes of young Catholic pilgrims to Rome.
The young people came from some 160 countries, sleeping in convents, schools, hotels and private homes around Rome after months of fund-raising and saving for plane or train tickets. Rome, for its part, was emptied of perhaps two-thirds of its 3 million people for Italy's traditional mid-August beach break.
Newspapers said organizers of Sunday's Mass were having to break communion wafers into pieces, caught short despite long shifts by baker nuns.
John Paul started Youth Days in 1985, seeking to inspire young Catholics as other faiths gained followers in much of the world. The first one, in central Rome, drew about 200,000 people, some waving banners of the then-banned Solidarity movement in John Paul's Poland.
The biggest crowd in John Paul's papacy was a World Youth Day gathering in 1995, which drew some 4 million people in the Philippines.
This week, young Catholics walked through the dark or for hours along sun-blanched streets to reach the Tor Vergata site of the latest Youth Day edition.
Amelisa Radeghieri, 24, of the northern city of Reggio Emilia, camped out overnight Friday just to get a good spot after being shut out of a glimpse of the pope at the 1997 edition in Paris.
''We wanted to get the first spot - and we got it,'' Radeghieri said.