Where is everyone? People took to their bikes in Copenhagen

Well over 1,000 towns and cities, among them many capitals, took part in the scheme backed by the European Union - with mixed success.

Bikes reigned in the Danish capital, Copenhagen, but early morning traffic jams were reported in Athens.

The initiative aims to give urbanites a taste of their town without traffic.

The car-free city concept, spearheaded by Paris in 1998, is intended to highlight public transport alternatives to the car.

Calmer streets?

Organisers say seeing a city without traffic may jolt its population into realising that cars are not an essential part of the urban landscape.

"The initiative is mainly to let people realise that living without cars is possible - it might even be fun," Stephan von Pohl of the World Car-free network told BBC News Online from Prague.

Not everyone was thrilled with the concept of abandoning their cars

"Crossing town by taking the metro is often quicker than battling through the streets."

A single day with reduced traffic, noise and pollution can give a glimpse of a higher quality of life for people who live in towns, he said.

The BBC's Katya Adler in Madrid, where road traffic accidents soar during the summer months, said Spain had warmly embraced the concept, with over 200 towns taking part.

In Paris, eight central districts were closed to cars and police said traffic was moving smoothly, according to AFP.

However in Athens roads were reported to be clogged by early-morning traffic as people attempted to get to work before the ban began.

And several cities - including Rome, famous for its reckless drivers, Berlin and Budapest - thought it best to avoid banning cars from the centre midweek.

Pal Vajda, the director of traffic services in Budapest told AFP that the 1.1 million motorists who drive to work each day "would not tolerate such an initiative."