With only six months to go before the London 2012 Olympics begin, the city is busy preparing for this grand event. But in Beijing, there's been lots of talk recently, about just how well the Olympic venues have been managed over the past four years.

In Beijing, there's been lots of talk recently, about just how well the Olympic venues have been managed over the past four years.

Once the grand Olympic Party is over, the biggest challenge left for host countries is how to make full use of the Olympic venues and see returns on the money invested in those iconic buildings. For most countries, this seems to be a mission impossible, even with well prepared plans.

Before construction began, plans were devised to ensure efficient use of Beijing's Olympic venues after the Games. Now three and a half years later, debate over this issue is still raging. The operation of venues like the Birds' Nest and the Water Cube is once again raising public concern.

One main concern for these venues is how to generate revenue - at least enough to cover running costs.

Yang Qiyong, deputy general manager of Beijing National Aquatics Center, said, "Ticket sales is still the major source of revenue. But as the effect of the Olympic Games gradually fades away, we are facing more pressure. We've managed to make ends meet last year by creating new channels of revenue, but it's really not an easy job."

But Beijing is already well ahead of many other Olympic host cities. Most Olympic venues in Beijing were built in universities and parks so they still attract plenty of users. The Birds' Nest and the Water Cube also manage to use their iconic influence to host important events.

Yang Qiyong said, "Last year, we received over two million tourists and organized 151 large scale events. That includes matches, commercial shows and promotional activities. All these bring us a stable source of income."

But revenue is not the only measure of success. Up holding the Olympic legacy is equally important. Many tourists are here not just for fun, but to revisit the memory of the Olympic Games.

A tourist said, "The Olympic Games were held here, so I come to visit the memory of the Olympics, feel its legacy and culture. It feels really good to come back again."

For the Water Cube, giving the public the opportunity to re-live the Olympics is a mission as important as creating revenue.

Yang Qiyong said, "We plan to open the swimming pools used for Olympic matches to the public, so that visitors can experience the place where gold medalists broke several records. There is also a social value to this iconic venue."

For the general public, the social function of the Olympic venues is something that really matters because after all, the Olympics is just an event, but the Olympic spirit is something here to stay.