Thousands of people attended a Tomorrow Festival Thursday at United Nations Plaza where the charter for the world organization was signed 60 years ago.

Music, speeches and the latest in "green technologies" are to be woven into the festivities for the mayors of 66 cities as far afield as Istanbul, to London, Shanghai, Zurich, Calcutta and Panama City.

The world's largest assembly of hydrogen fuel cell cars and buses were on display in a plaza across from San Francisco City Hall, where the mayors are meeting to finalize an accord detailing ways they intend to make cities more harmonious with nature.

The conference marks the first time the UN has held its annual World Environment in the United States.

More than 300 events, both sanctioned and unofficial, have been organized in the spirit of the gathering, according to San Francisco's progressive Mayor Gavin Newsom.

The mayors Thursday toured a recycling facility where everything from construction material to gourmet restaurant meal scraps are converted to new uses.

There has been tremendous interest in the city's program that composts leftovers from San Francisco eateries for use as fertilizer at farms and vineyards.

"It is kind of cute that kitchen scraps go into fine winds that can wind up costing more than 80 dollars a bottle," said Robert Reed of Norcal Waste Systems, the city's trash handler.

Black, Latino, Asian and Native American environmental leaders will share concerns at a Commonwealth Club gathering dubbed "Green Cities, Brown Folks: Responsible and Just Urban Environments."

Youth accords were scheduled to harness energy and input from teenagers in the battle for the environment's future. There will also be a dance music party and green-themed alternative music concert A Green Screen environmental festival will play out at the Castro Theater in the city's well-known gay district.

London's mayor, Ken Livingstone, is to speak Friday during tour of the powerhouse that drives San Francisco's famous cable cars that trundle up and down its breathtakingly steep hills.

The mayors will stroll restored marshland near the base of the Golden Gate Bridge, hike in Muir Woods, and visit a nature museum.

An "eco-chic" fashion show will feature runway models in nature friendly garb including a dress made of organic flowers. The organic flower industry will be the subject of a symposium on Friday involving more than 125 industry experts and dignitaries.

What is being billed as the world's largest flower globe will be built

outside City Hall.

Former US vice president Al Gore is to give a Powerpoint presentation at a dinner Saturday night to be held under the theme Urban Power. On Sunday, a 500-strong choir is to sing a world debut of a song titled "United Nations, Together We Can."

"It is time for the world to sing a different tune about the environment" said Gerald Prolman, chief executive of Organic Bouquet Inc. and producer of the song.

"What better way to inspire environmental activism than through a spiritually uplifting song."

The event is to culminate Sunday with the mayors signing an accord binding them to meet goals regarding protecting the air, water and land.

California's celebrity governor, Arnold Schwarzenegger, opene the five-day confernce on Wednesday by soigning a decree settiung tough new greenhouse gas emission targets in a bid to counter global warming.

The decree provides that greenhouse gas emissions in California be cut to year 2000 levels in the next five years, and that they be 80 percent below 1990 levels by 2050.

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