Pretty but noisy Paris, its gracious Old World buildings blackened by exhaust fumes, is going car-less for a day.

Paris Mayor Anne Hidalgo presided over Sunday's "day without cars," two months before the city hosts the global summit on climate change.

Mayors from Sao Paulo, Brazil, Brussels and Bristol were in Paris for the kick-off on the famed Champs-Elysees Avenue.

The avenue, normally congested with vehicles, isn't the only sector of Paris having a carless moment. Vehicles, including motorized bicycles, are forbidden in a quarter of the French capital and "strongly not recommended" throughout. Those who hit the road anyway must observe a 20 kilometer-per-hour (12.5 mph) speed limit. Police are watching.

Buses, ambulances, police vehicles, fire trucks and taxis were allowed in the streets.