The unveiling ceremony will be held at the Capital Museum of China, at which the medals will be displayed and the concept behind their design explained.

To mark the start of the 500-day countdown, about 40 sports and cultural activities will be held across the capital this week.

Ahead of those, two mass-participation events were held yesterday morning the 2007 International Long Walk Carnival and the 2007 International Long Distance Running Festival. Both attracted tens of thousands of people who were keen to show their enthusiasm for the Games by running or walking their way around the city.

The fourth Long Walk Carnival, which was held at eastern Beijing's Chaoyang Park, attracted more than 10,000 participants, who tackled an 18-kilometer course divided into five laps to represent the five Olympic rings. Those who managed to finish were awarded a certificate and a commemorative "volunteer smile" wristband.

"I'm very happy to have been part of this promotion for the Beijing Games. It was great to see the Olympic spirit of participation," Zhang Li, a college student from Beijing, said.

Of the events planned for this week, some of the most significant relate to the Beijing 2008 volunteer program.

The slogan for the program will be announced at a special ceremony this evening, at which the city's 10 best volunteers from last year will also be recognised. Also, on Wednesday, the recruitment of volunteers from overseas will begin.

The aim of this week's events is to involve as many people as possible in the preparations for next year's Games, which follows the theme of, "I Participate, I Contribute and I Enjoy".

The events include table tennis competitions among local communities, a concert featuring Olympic songs, and an exhibition of classic moments from past Games.