Initial content on the site includes the result of requests for contributions from the community, such as "images that sum up your city", making use of the Guardian's relatively new crowdsourcing app GuardianWitness.
With content being commissioned from bloggers, journalists and other experts, the site aims to act as "a really good hub for discussing all these issues", Mike Herd, editor of the site, told Journalism.co.uk.
"What we want the site to do is really be led by people who have really interesting ideas in this area," he explained, "that means we need to find ways of taking what people are saying and developing that in different ways."
The site also offers a map which collects together links to "the best city blogs around the world".
"We want to have a sense of people who know these things intimately and that's a really good resource," Herd said.
But Herd stressed that the final content published by the Cities site will be commissioned and carefully selected, and it will also not be "hosting blogs and pumping out their content".
"We want to be thoughtful and considered but led by the issues that our readers are raising, looking at comments and hosting live debates."
It is hoped that this sort of approach will help to foster an environment where the site's "readers and our community can not just be commenting on stories but really taking part in stories".
As an example, Herd said the site is planning on publishing an article by "a Canadian scientist" which will draw on their efforts to "trial different urban landscapes on people using virtual reality simulations". In this case, the site's own audience will be given a chance to be involved in that research, including through the completion of a questionnaire.
"The Guardian can offer a large, diverse audience which is quite appealing to someone doing research," Herd said.
As well as using GuardianWitness to allow the community to share content with the site, Herd explained that there are also plans to harness the power of the Instagram community later this week to get an understanding of the different commuting experiences from city to city.
Another possible "experiment" might be to create a "working group" of some of those who comment on the site, he added, who could engage around suggestions for ways of "future-proofing cities".
For now the site will try out these different forms of engagement and assess the results. Herd said that once the site becomes a place featuring "really strong conversations" about cities from one country to another, "that's when I think it will be a success".
According to the press release Guardian Cities was launched "in collaboration with the Rockefeller Foundation".