The airport and train station are closing down Friday afternoon and residents used to bustle at the height of summer vacations say the streets are empty.
The city center is almost deserted, and the seaside around the casino where leaders will meet is under lockdown.
Cars are thoroughly checked and tourists can no longer access their usual haunts.
Philippe Haguet says the gift shop he owns has been empty for the past two days.
Leaders of the Group of Seven countries arrive on Saturday to discuss issues including the struggling global economy and climate change until Monday. They include the United States, Germany, Japan, Britain, France, Canada and Italy.
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