|Anti-G8 protesters' aim is to|
Several thousand protestors also massed in the nearby French town of Annemasse to join the main protest on the opening day of the summit.
Up to 100,000 people are expected to take part in the protest.
Many banks, shops and businesses in Geneva's chic downtown have shut up shop for several days as a precaution against violent demonstrations. Many intend to remain closed until early next week.
The area where the UN and other organisations are situated will be off-limits on Sunday.
Sunday's action is expected to begin with symbolic blockades of bridges in Geneva and across roads in Annemasse to try hold up delegates headed for Evian.
The are staying in "alternative" villages and will be marching simultaneously on either side of the border and meeting up at a border-crossing.
Some 3,000 people took part in a warm-up protest in Geneva on Friday in front of the United Nations building and other international organisations.
People from Britain, Switzerland and Germany took part in the largely peaceful protest march under the banner "No Borders", shouting slogans such as "No Border, No Deportation" and "No to the Occupation of Iraq".
After protesting outside the World Trade Organisation (WTO), they marched towards the UN, throwing stones at the Russian mission on the way.
In another demonstration, some 200 protestors on bicycles blocked a roundabout in front of the offices of food giant Nestle.
The first anti-G8 demonstration took place late on Thursday in the Swiss city of Lausanne, which faces Evian across Lake Geneva.
The rally took passed off largely peacefully and in a party-like atmosphere. A small group among the 5,000 participants tried in vain to provoke police by throwing cans.
The protests are aimed at registering discontent at the economic and political policies of the world's eight leading industrialised nations.