Organisers expect 500,000 at Randwick

World Youth Day organisers say they expect 500,000 pilgrims to gather for tonight's vigil with the Pope at Sydney's Randwick Racecourse.

World Youth Day communications directorJim Hanna says more than 3,000 toilets have been constructed for the event, as well as 18 kilometres of temporary fencing and 22 kilometres of crowd-control barriers.

He says there will be live performances for pilgrims from midday today to keep them entertained in the lead-up to the vigil at 7.00pm.

Mr Hanna says the expected crowds will temporarily give Randwick one of the largest populations in the country.

"It will be the 10th largest city in Australia for tonight," he said.

"To put it another way, the population of Randwick Racecourse will be greater than that of the whole Northern Territory, all in one place."

Greg Rochford from the ambulance service is warning the pilgrims to rug up as they wait for tomorrow's final mass.

"The minimum temperature is expected to be seven (degrees), that's cold enough for hypothermia," he said.

Organisers say the mass could attract a crowd of 500,000.

The Sydney Harbour bridge has been awash today with fluttering flags from every corner of the world and thousands of singing and chanting pilgrims, carrying sleeping bags and backpacks as they make their way to the racecourse.

New South Wales Premier Morris Iemma joined the pilgrims in walking across the bridge around lunchtime.

Several hundred protesters gathered near the bridge to protest against the Pope and the Catholic Church's stance on abortion and condoms.

Police have separated the chanting demonstrators from the pilgrims by positioning them on the opoosite side of a garden bed.

They say they are planning to hand out 6,000 condoms to pilgrims.

They also demonstrated against the Church's handling of sexual abuse cases.