100,000 pilgrims expected at WYD opening mass

More than 100,000 pilgrims are expected to attend the first major event of World Youth Day in Sydney today, the opening mass.

About 60 eager pilgrims from countries including Spain and Canada marked the start of the World Youth Day festival overnight, gathering at St Mary's Cathedral next to Sydney's Hyde Park to watch the clock strike midnight.

While Pope Benedict enjoys another day of relaxation at a retreat in north-west Sydney, the city's Catholic Archbishop, Cardinal George Pell, will officially open World Youth Day this afternoon.

He will lead the two-hour opening mass at Barangaroo from 4:30pm (AEST).

The World Youth Day cross and icon will arrive at the site during the mass after a journey around Australia and the world.

World Youth Day coordinator Bishop Anthony Fisher says Cardinal Pell's homily will come from one the most spectacular but also terrifying passages in the Bible, known as the 'Valley of Dry Bones'.

"It's evocative for Australians because we've been in drought now for more than a decade and some of our farms look like that, dried out with the carcasses and now just the bones of the dead animals," he said.

The mass will be followed by a concert, which is expected to run well into the evening.

George St closes

Extensive road closures and clearways come into effect in the Sydney CBD today for the official beginning of the celebrations.

George Street will be closed from 10:00am to midnight each day until Friday.

There will be up to 500 special event clearways and about 300 road closures this week.

The New South Wales Government spokeswoman for World Youth Day, Kristina Keneally, says motorists who still choose to drive in and around the city can expect significant delays and detours.

"We've said that the CBD will be no place for cars during World Youth Day week," she said.

"All of the road closures are on the Roads and Traffic Authority website.

"I strongly urge people to check out the RTA website and the 131 500 number, plan your travel ahead and use public transport."

The RTA, the State Government and World Youth Day organisers all said there were too many motorists in the CBD yesterday, even though there were no major traffic problems.

The Government wants a 30 per cent reduction in traffic this week but it was only down by around 9 per cent yesterday.